Simple vs Compound Interest: What You Need to Know

Author
Grace Lemire
Grace Lemire
author

Grace Lemire is a freelance writer and editor with over five years of experience in the personal finance industry. She has been featured on a variety of publications, including NPR, CNN, FinanceBuzz, Dollar Geek, Pangea, and True Finance. Her work focuses on the intersection of personal finance and technology. In 2023, Grace was nominated for the Best Personal Finance Advice award in Debt.com’s FinTok Awards.

See author page
Edited by
Emma Östlund
Emma Östlund
editor

Emma Östlund works as a business operations analyst at Sparrow. Emma studied Psychology, Computer Science, and Markets & Management at Duke University. With a well-rounded background in business and analytics, Emma strives to deliver data-driven conclusions and insights.

See author page
Reviewed by
Camden Ford
Camden Ford
reviewer

Camden leads Sparrow’s business operations – everything from product management to business analytics. After graduating Cum Laude from Duke University where he studied Civil Engineering, Camden worked as a Consultant for A.T. Kearney where he worked in their Strategic Operations practice. With a strong background in analytics, Camden strives to deliver data-driven conclusions and insights.

See author page
Updated
January 13, 2024

Interest, often expressed as a percentage, is the cost of borrowing money from a lender. It can be one of two types: simple or compound. The difference between simple and compound interest lies in how they are calculated. While seemingly small differences in their formulas, the type of interest on a loan can drastically change what you pay over time.

Here’s what you need to know about simple vs compound interest.

Get pre-qualified in just 2 minutes
Check your rates across multiple lenders to get accurate, pre-qualified rates with no impact to your credit score

Simple Interest vs Compound Interest

What is Simple Interest?

Simple interest is calculated based on the principal of the loan, or the amount you originally borrowed. So, in other words, the amount of interest you accrue each month will only be calculated based on the amount you initially borrowed.

What is Compound Interest?

Compound interest is calculated based on the principal of the loan plus any unpaid interest accrued on the loan. So, over time, interest will accrue on top of both the principal and any previously accrued interest.

Simple vs Compound Interest Example

Let’s say you had a principal loan balance of $30,000. For simplicity’s sake, let’s say it costs you $3 per day in interest to borrow that money.

With simple interest, it will cost you $90 per 30-day month in interest. ($3 x 30 days = $90)

With compound interest, your balance would increase to $30,003 on the first day. The next day, the interest amount would be calculated on a balance of $30,003, not the principal balance of $30,000. So, over time, the interest can accrue quite quickly as it compounds on itself.

The latest rates from Sparrow’s partners

If you want to skip pre-qualification and apply directly with a lender, you can do so by clicking Apply below.

logo
Compare your personalized, pre-qualified rates from these lenders in minutes.
Find my rates

Which is Better: Simple or Compound Interest?

If you have the option to choose between simple and compound interest, we recommend selecting simple interest.

Simple interest will often cost you less over time than compound interest because you will only pay interest on your principal loan balance. With compound interest, you will pay interest on your interest (say that 10x fast), which will inevitably cost you more over the life of your loan.

Here’s an example of how simple and compound interest would impact how much you pay over the life of the same loan.

Simple Interest

Compound Interest*

Principal Balance

$30,000

$30,000

Interest Rate

5.8%

5.8%

Repayment Period

15 years

15 years

Total Paid Over the Life of the Loan

$56,100

$69,888

Total Interest Paid Over the Life of the Loan

$26,100

$39,888

*Compounded quarterly. Loans will compound on different frequencies. How often the interest compounds can drastically change how much you pay over time.

While the two loans have the same principal balance, interest rate, and repayment period, the loan with compound interest would cost you $13,788 more over the life of the loan.

Are Student Loans Simple or Compound Interest?

All federal student loans operate on simple interest, and the vast majority of private student loans do, too. However, some private student loans do operate on compound interest, which often compound daily. To verify how your student loan interest is calculated, check with your lender directly.

Once you know how your student loan interest is being calculated, you can estimate your overall interest cost. To do so, use the simple and compound interest formulas.

Simple interest loans: Principal x interest rate x loan term = simple interest

Compound interest loans: (Principal (1 + interest rate)^ Number of compounding periods in a year) – principal = compound interest

As you can tell, the compound interest formula is a bit more complicated than the simple interest formula. If you have trouble doing the calculation by hand, you can utilize a compound interest calculator to help you.

How to Save on Student Loan Interest

Interest is often a major expense when it comes to borrowing a student loan. In fact, the average student loan accrues $26,000 in interest over the course of 20 years.

While opting for a simple interest loan is a great start to minimizing interest costs, there are a variety of ways to minimize it even further.

>> MORE: What is the average student loan interest rate?

Refinance Your Student Loan(s) 

Refinancing your student loan debt can result in significant savings in interest. In fact, borrowers who used Sparrow to refinance reduced their interest rate by 2.29 percentage points, saving them approximately $17,000 over the life of their new loan, on average.

>> MORE: Refinance student loans: Compare the best lenders

When you refinance, you essentially take out a new loan with a better interest rate or terms and then use the new loan to pay off your old loan.

Easily refinance your student loans
Compare rates from up to 17 lenders in as little as 2 minutes

Here’s how a 2.29% interest rate reduction could impact how much you pay over the life of your loan.

Principal Balance

Initial Interest Rate

Expected Total Payment Over the Life of the Loan

Interest Rate After Refinancing with Sparrow (Initial Interest Rate – Average 2.29% Savings in Interest) 

Expected Total Payment Over the Life of the Loan with the New Interest Rate* 

Savings from Refinancing

$10,000

8%

$17,202

5.71%

$14,909

$2,293

$30,000

6.5%

$47,040

4.21%

$40,514

$6,526

$50,000

5%

$71,171

2.71%

$60,905

$10,266

*Note that these numbers are based on a full 15-year repayment term, prior to making payments on the initial loan. The calculations will change based on how far into your repayment period you are, any surplus payments you may have made, and the new loan term you choose.

Add a Cosigner to the Loan

A cosigner is an individual who signs onto a loan alongside you, taking legal responsibility for paying back the loan should you fail to do so. A creditworthy cosigner gives lenders a “second line of defense,” if you will, lowering the risk for them to lend to you.

As a result, lenders will often offer you a lower interest rate on your student loan if you have a creditworthy individual cosign your loan.

>> MORE: What is a private student loan cosigner?

Negotiate Your Interest Rate

Believe it or not, you can actually negotiate your student loan interest rate. While it isn’t 100% effective, it can’t hurt to call up your loan servicer and ask for a lower interest rate.

See if the Lender Offers an Autopay Discount

Many private student lenders offer an interest rate discount, often 0.25%, for opting into autopay. By opting in to autopay, your student loan payments will automatically be withdrawn from your account each month.

You should only opt in to autopay, however, if you are absolutely positive it will not result in an overdraft of your account.

>> MORE: How to save thousands on student loans with an autopay discount

Student loan rates from our partners
lender Ascent logo
Ascent
Minimum credit score
Varies
Fixed APR
Fixed APR

Ascent’s undergraduate and graduate student loans are funded by Bank of Lake Mills, or DR Bank, each Member FDIC. Loan products may not be available in certain jurisdictions. Certain restrictions, limitations; and terms and conditions may apply. For Ascent Terms and Conditions please visit: www.AscentFunding.com/Ts&Cs. Rates are effective as of 4/1/2024 and reflect an automatic payment discount of either 0.25% (for credit-based loans) OR 1.00% (for undergraduate outcomes-based loans). Automatic Payment Discount is available if the borrower is enrolled in automatic payments from their personal checking account and the amount is successfully withdrawn from the authorized bank account each month. For Ascent rates and repayment examples please visit: AscentFunding.com/Rates. 1% Cash Back Graduation Reward subject to terms and conditions. Cosigned Credit-Based Loan student must meet certain minimum credit criteria. The minimum score required is subject to change and may depend on the credit score of your cosigner. Lowest rates require interest-only payments, the shortest loan term, a cosigner, and are only available for our most creditworthy applicants and cosigners with the highest average credit scores. Actual APR offered may be higher or lower than the repayment examples above, based on the amount of time you spend in school and any grace period you have before repayment begins.

4.09 - 15.66%
Variable APR
Variable APR

Ascent’s undergraduate and graduate student loans are funded by Bank of Lake Mills, or DR Bank, each Member FDIC. Loan products may not be available in certain jurisdictions. Certain restrictions, limitations; and terms and conditions may apply. For Ascent Terms and Conditions please visit: www.AscentFunding.com/Ts&Cs. Rates are effective as of 4/1/2024 and reflect an automatic payment discount of either 0.25% (for credit-based loans) OR 1.00% (for undergraduate outcomes-based loans). Automatic Payment Discount is available if the borrower is enrolled in automatic payments from their personal checking account and the amount is successfully withdrawn from the authorized bank account each month. For Ascent rates and repayment examples please visit: AscentFunding.com/Rates. 1% Cash Back Graduation Reward subject to terms and conditions. Cosigned Credit-Based Loan student must meet certain minimum credit criteria. The minimum score required is subject to change and may depend on the credit score of your cosigner. Lowest rates require interest-only payments, the shortest loan term, a cosigner, and are only available for our most creditworthy applicants and cosigners with the highest average credit scores. Actual APR offered may be higher or lower than the repayment examples above, based on the amount of time you spend in school and any grace period you have before repayment begins.

6.22 - 16.08%
lender LendKey logo
LendKey
Minimum credit score
660
Fixed APR
Fixed APR

1 – Terms and Conditions Apply

Loan products, terms, and benefits may be modified or discontinued by participating lenders at any time without notice. Rates displayed are reserved for the most creditworthy consumers who enroll to make automatic monthly payments. Your initial rate will be determined after a review of your application and credit profile. Variable rates may increase after consummation. You must be either a U.S. citizen or Permanent Resident in an eligible state and from an eligible school, and meet the lender’s credit and income requirements to qualify for a loan. Certain membership requirements (including the opening of a share account, a minimum share account deposit, and the payment of any applicable association fees in connection with membership) may apply in the event that an applicant wishes to apply with, and accept a loan offered from, a credit union lender. If you are not a member of the credit union lender, you may apply and become a member during the loan application process if you meet the lender’s eligibility criteria. Applying with a creditworthy cosigner may result in a better chance of loan approval and/or lower interest rate. Loans for exam preparation classes, including, but not limited to, loans for LSAT, MCAT, GMAT, and GRE preparation, are not available via LendKey.com.

2 – Cosigner Release

Some lenders participating on LendKey.com may offer the benefit of cosigner release. Cosigner release is subject to lender approval. In order to qualify, the borrower, alone, must meet the following requirements: (1) Make the required number of consecutive, on-time full principal and interest payments as indicated in the borrower’s credit agreement during the repayment period (excluding interest-only payments) immediately prior to the request. Any period of forbearance will reset the repayment clock; (2) The account cannot be in delinquent status; (3) The borrower must provide proof of income indicating that he/she meets the income requirements and pass a credit review demonstrating that he/she has a satisfactory credit history and the ability to assume full responsibility of loan repayment; (4) No bankruptcies or foreclosures in the last sixty months; and (5) No loan defaults.

3 – Autopay Rate Reduction

Subject to floor rate and may require the automatic payments be made from a checking or savings account with the lender. The rate reduction will be removed and the rate will be increased by 0.25% upon any cancellation or failed collection attempt of the automatic payment and will be suspended during any period of deferment or forbearance. As a result, during the forbearance or suspension period, and/or if the automatic payment is canceled, any increase will take the form of higher payments.

4 – AutoPay Discount & Lowest Interest Rate

Subject to floor rate and may require the automatic payments be made from a checking or savings account with the lender. The rate reduction will be removed and the rate will be increased by 0.25% upon any cancellation or failed collection attempt of the automatic payment and will be suspended during any period of deferment or forbearance. As a result, during the forbearance or suspension period, and/or if the automatic payment is canceled, any increase will take the form of higher payments. The lowest advertised APR is only available for loan terms of 10 years and is reserved for the highest qualified applicants, taking into consideration the applicant’s credit and other factors.

4.39 - 10.39%
Variable APR
Variable APR

1 – Terms and Conditions Apply

Loan products, terms, and benefits may be modified or discontinued by participating lenders at any time without notice. Rates displayed are reserved for the most creditworthy consumers who enroll to make automatic monthly payments. Your initial rate will be determined after a review of your application and credit profile. Variable rates may increase after consummation. You must be either a U.S. citizen or Permanent Resident in an eligible state and from an eligible school, and meet the lender’s credit and income requirements to qualify for a loan. Certain membership requirements (including the opening of a share account, a minimum share account deposit, and the payment of any applicable association fees in connection with membership) may apply in the event that an applicant wishes to apply with, and accept a loan offered from, a credit union lender. If you are not a member of the credit union lender, you may apply and become a member during the loan application process if you meet the lender’s eligibility criteria. Applying with a creditworthy cosigner may result in a better chance of loan approval and/or lower interest rate. Loans for exam preparation classes, including, but not limited to, loans for LSAT, MCAT, GMAT, and GRE preparation, are not available via LendKey.com.

2 – Cosigner Release

Some lenders participating on LendKey.com may offer the benefit of cosigner release. Cosigner release is subject to lender approval. In order to qualify, the borrower, alone, must meet the following requirements: (1) Make the required number of consecutive, on-time full principal and interest payments as indicated in the borrower’s credit agreement during the repayment period (excluding interest-only payments) immediately prior to the request. Any period of forbearance will reset the repayment clock; (2) The account cannot be in delinquent status; (3) The borrower must provide proof of income indicating that he/she meets the income requirements and pass a credit review demonstrating that he/she has a satisfactory credit history and the ability to assume full responsibility of loan repayment; (4) No bankruptcies or foreclosures in the last sixty months; and (5) No loan defaults.

3 – Autopay Rate Reduction

Subject to floor rate and may require the automatic payments be made from a checking or savings account with the lender. The rate reduction will be removed and the rate will be increased by 0.25% upon any cancellation or failed collection attempt of the automatic payment and will be suspended during any period of deferment or forbearance. As a result, during the forbearance or suspension period, and/or if the automatic payment is canceled, any increase will take the form of higher payments.

4 – AutoPay Discount & Lowest Interest Rate

Subject to floor rate and may require the automatic payments be made from a checking or savings account with the lender. The rate reduction will be removed and the rate will be increased by 0.25% upon any cancellation or failed collection attempt of the automatic payment and will be suspended during any period of deferment or forbearance. As a result, during the forbearance or suspension period, and/or if the automatic payment is canceled, any increase will take the form of higher payments. The lowest advertised APR is only available for loan terms of 10 years and is reserved for the highest qualified applicants, taking into consideration the applicant’s credit and other factors.

6.09 - 11.33%
lender Earnest logo
Earnest
Minimum credit score
650
Fixed APR
Fixed APR

Auto Pay Discount Disclosure

You can take advantage of the Auto Pay interest rate reduction by setting up and maintaining active and automatic ACH withdrawal of your loan payment. The interest rate reduction for Auto Pay will be available only while your loan is enrolled in Auto Pay. Interest rate incentives for utilizing Auto Pay may not be combined with certain private student loan repayment programs that also offer an interest rate reduction. For multi-party loans, only one party may enroll in Auto Pay.

Student Loan Origination (Private Student Loan) Interest Rate Disclosure

Actual rate and available repayment terms will vary based on your income. Fixed rates range from 4.36% APR to 16.15% APR (excludes 0.25% Auto Pay discount). Variable rates range from 5.87% APR to 16.45% APR (excludes 0.25% Auto Pay discount). Earnest variable interest rate student loan origination loans are based on a publicly available index, the 30-day Average Secured Overnight Financing Rate (SOFR) published by the Federal Reserve Bank of New York. The variable rate is based on the rate published on the 25th day, or the next business day, of the preceding calendar month, rounded to the nearest hundredth of a percent. The rate will not increase more than once per month. Although the rate will vary after you are approved, it will never exceed 36% (the maximum allowable for this loan). Please note, Earnest Private Student Loans are not available in Nevada. Our lowest rates are only available for our most credit qualified borrowers and contain our .25% auto pay discount from a checking or savings account. It is important to note that the 0.25% Auto Pay discount is not available while loan payments are deferred.

Earnest Private Student Loans are made by One American Bank, Member FDIC, or FinWise Bank, Member FDIC. One American Bank, 515 S. Minnesota Ave, Sioux Falls, SD 57104. Finwise Bank, 756 East Winchester, Suite 100, Murray, UT 84107

Earnest loans are serviced by Earnest Operations LLC, 535 Mission St., Suite 1663 San Francisco, CA 94105, NMLS #1204917, with support From Navient Solutions, LLC (NMLS #212430). One American Bank, FinWise Bank, and Earnest LLC and its subsidiaries, including Earnest Operations LLC, are not sponsored by agencies of the United States of America.

© 2024 Earnest LLC. All rights reserved.

4.11 - 15.90%
Variable APR
Variable APR

Auto Pay Discount Disclosure

You can take advantage of the Auto Pay interest rate reduction by setting up and maintaining active and automatic ACH withdrawal of your loan payment. The interest rate reduction for Auto Pay will be available only while your loan is enrolled in Auto Pay. Interest rate incentives for utilizing Auto Pay may not be combined with certain private student loan repayment programs that also offer an interest rate reduction. For multi-party loans, only one party may enroll in Auto Pay.

Student Loan Origination (Private Student Loan) Interest Rate Disclosure

Actual rate and available repayment terms will vary based on your income. Fixed rates range from 4.36% APR to 16.15% APR (excludes 0.25% Auto Pay discount). Variable rates range from 5.87% APR to 16.45% APR (excludes 0.25% Auto Pay discount). Earnest variable interest rate student loan origination loans are based on a publicly available index, the 30-day Average Secured Overnight Financing Rate (SOFR) published by the Federal Reserve Bank of New York. The variable rate is based on the rate published on the 25th day, or the next business day, of the preceding calendar month, rounded to the nearest hundredth of a percent. The rate will not increase more than once per month. Although the rate will vary after you are approved, it will never exceed 36% (the maximum allowable for this loan). Please note, Earnest Private Student Loans are not available in Nevada. Our lowest rates are only available for our most credit qualified borrowers and contain our .25% auto pay discount from a checking or savings account. It is important to note that the 0.25% Auto Pay discount is not available while loan payments are deferred.

Earnest Private Student Loans are made by One American Bank, Member FDIC, or FinWise Bank, Member FDIC. One American Bank, 515 S. Minnesota Ave, Sioux Falls, SD 57104. Finwise Bank, 756 East Winchester, Suite 100, Murray, UT 84107

Earnest loans are serviced by Earnest Operations LLC, 535 Mission St., Suite 1663 San Francisco, CA 94105, NMLS #1204917, with support From Navient Solutions, LLC (NMLS #212430). One American Bank, FinWise Bank, and Earnest LLC and its subsidiaries, including Earnest Operations LLC, are not sponsored by agencies of the United States of America.

© 2024 Earnest LLC. All rights reserved.

5.62 - 16.20%
lender College Ave logo
College Ave
Minimum credit score
Mid-600s
Fixed APR
Fixed APR

College Ave Student Loans products are made available through Firstrust Bank, member FDIC, First Citizens Community Bank, member FDIC, or M.Y. Safra Bank, FSB, member FDIC. All loans are subject to individual approval and adherence to underwriting guidelines. Program restrictions, other terms, and conditions apply.

*The 0.25% auto-pay interest rate reduction applies as long as the borrower or cosigner, if applicable, enrolls in auto-pay and authorizes our loan servicer to automatically deduct your monthly payments from a valid bank account via Automated Clearing House (“ACH”). The rate reduction applies for as long as the monthly payment amount is successfully deducted from the designated bank account and is suspended during periods of forbearance and certain deferments. Variable rates may increase after consummation. $5,000 is the minimum requirement to refinance. The maximum loan amount is $300,000 for those with medical, dental, pharmacy or veterinary doctorate degrees, and $150,000 for all other undergraduate or graduate degrees. Information advertised valid as of 08/25/2022. Variable interest rates may increase after consummation.

This informational repayment example uses typical loan terms for a refi borrower with a Full Principal & Interest Repayment and a 10-year repayment term, has a $40,000 loan and a 5.5% Annual Percentage Rate (“APR”): 120 monthly payments of $434.11 while in the repayment period, for a total amount of payments of $52,092.61. Loans will never have a full principal and interest monthly payment of less than $50. Your actual rates and repayment terms may vary.

This informational repayment example uses typical loan terms for a freshman borrower who selects the Deferred Repayment Option with a 10-year repayment term, has a $10,000 loan that is disbursed in one disbursement and a 8.35% fixed Annual Percentage Rate (“APR”): 120 monthly payments of $179.18 while in the repayment period, for a total amount of payments of $21,501.54. Loans will never have a full principal and interest monthly payment of less than $50. Your actual rates and repayment terms may vary.

Information advertised valid as of 3/07/2024. Variable interest rates may increase after consummation. Approved interest rate will depend on creditworthiness of the applicant(s), lowest advertised rates only available to the most creditworthy applicants and require selection of full principal and interest payments with the shortest available loan term.

4.07 - 15.48%
Variable APR
Variable APR

College Ave Student Loans products are made available through Firstrust Bank, member FDIC, First Citizens Community Bank, member FDIC, or M.Y. Safra Bank, FSB, member FDIC. All loans are subject to individual approval and adherence to underwriting guidelines. Program restrictions, other terms, and conditions apply.

*The 0.25% auto-pay interest rate reduction applies as long as the borrower or cosigner, if applicable, enrolls in auto-pay and authorizes our loan servicer to automatically deduct your monthly payments from a valid bank account via Automated Clearing House (“ACH”). The rate reduction applies for as long as the monthly payment amount is successfully deducted from the designated bank account and is suspended during periods of forbearance and certain deferments. Variable rates may increase after consummation. $5,000 is the minimum requirement to refinance. The maximum loan amount is $300,000 for those with medical, dental, pharmacy or veterinary doctorate degrees, and $150,000 for all other undergraduate or graduate degrees. Information advertised valid as of 08/25/2022. Variable interest rates may increase after consummation.

This informational repayment example uses typical loan terms for a refi borrower with a Full Principal & Interest Repayment and a 10-year repayment term, has a $40,000 loan and a 5.5% Annual Percentage Rate (“APR”): 120 monthly payments of $434.11 while in the repayment period, for a total amount of payments of $52,092.61. Loans will never have a full principal and interest monthly payment of less than $50. Your actual rates and repayment terms may vary.

This informational repayment example uses typical loan terms for a freshman borrower who selects the Deferred Repayment Option with a 10-year repayment term, has a $10,000 loan that is disbursed in one disbursement and a 8.35% fixed Annual Percentage Rate (“APR”): 120 monthly payments of $179.18 while in the repayment period, for a total amount of payments of $21,501.54. Loans will never have a full principal and interest monthly payment of less than $50. Your actual rates and repayment terms may vary.

Information advertised valid as of 3/07/2024. Variable interest rates may increase after consummation. Approved interest rate will depend on creditworthiness of the applicant(s), lowest advertised rates only available to the most creditworthy applicants and require selection of full principal and interest payments with the shortest available loan term.

5.59 - 16.69%

Final Thoughts from the Nest

The type of interest you have on a loan can drastically impact how much you pay over the life of the loan. So, before borrowing, consider whether the loan has simple or compound interest.

To explore a variety of student loan options at low interest rates, submit the Sparrow form.

Dive deeper in student loans