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Loan Interest Calculator

Calculate total interest paid on any loan with detailed amortization by payment frequency.

The total amount you are borrowing (the principal).
The yearly interest rate (APR) charged on the loan.
How many years you will take to repay the loan.
How often you make payments. More frequent payments slightly reduce total interest paid.
Payment (monthly) $471.78
Total Payments 60.00
Total Interest $3,306.80
Total Paid $28,306.80
Loan Amount $25,000.00
Editorial Standard

GetCalcu Methodology & Editorial Standards

Reviewed: September 2026

Consumer Financial Protection Bureau (CFPB) Regulation Z (12 CFR § 1026.22) & Truth in Lending Act (TILA) amortization standards.

Reference Sources: GetCalcu Consumer Credit & Lending Review Board

How to Calculate Total Interest Paid on a Loan

Understanding the true cost of borrowing means looking beyond the monthly payment. The GetCalcu Loan Interest Calculator reveals the total interest you will pay and how your payment frequency — monthly, biweekly, weekly, or quarterly — changes that cost over the life of the loan.

How Payment Frequency Reduces Interest

Making payments more frequently than monthly reduces total interest because principal is paid down sooner, so less interest accrues. Biweekly payments (26 per year) effectively add one extra monthly payment per year, shortening the loan and saving interest.

Reading the Amortization Schedule

The schedule shows every payment split into principal and interest. Watching the interest portion shrink over time reveals how accelerated payments front-load principal reduction and compound your interest savings.

How to Use the Loan Interest Calculator

  1. 1
    Enter the loan amount and annual interest rate (APR).
  2. 2
    Set the loan term in years.
  3. 3
    Choose how often you make payments — monthly, biweekly, weekly, or quarterly.
  4. 4
    Review the total interest, payment amount, and full amortization schedule.
  5. 5
    Switch payment frequency to see how much interest you can save.

Loan Interest Calculator Formula

Payment = P × [r(1+r)^n] / [(1+r)^n − 1] | Total Interest = (Payment × n) − P | r = APR ÷ payments per year, n = total payments

Real-World Worked Examples

These scenarios demonstrate how key input parameters alter your calculation outcome.

Monthly Payments

Input: Amount: $25,000, Rate: 5%, Term: 5 years, Monthly
Result: Payment: ~$472 | Total Interest: ~$3,307

Biweekly Saves Interest

Input: Amount: $25,000, Rate: 5%, Term: 5 years, Biweekly
Result: Payment: ~$236 | Total Interest: ~$3,064 (saves ~$243)

Frequently Asked Questions

How is total interest on a loan calculated?

Total interest equals (regular payment × total number of payments) − loan principal. For a $25,000 loan at 5% APR over 5 years with monthly payments, each payment is about $472, total payments are $28,307, so total interest is about $3,307. Our calculator computes this for any payment frequency.

Does paying biweekly instead of monthly save interest?

Yes. Biweekly payments mean 26 half-payments per year — equivalent to 13 monthly payments instead of 12. The extra payment and more frequent principal reduction lower total interest and shorten the loan. On a 5-year loan the savings can be a few hundred dollars; on a 30-year mortgage it can be tens of thousands.

What payment frequency saves the most interest?

More frequent payments save more interest because principal is reduced sooner. Weekly payments save slightly more than biweekly, which saves more than monthly. However, the biggest factor is the extra payment effect — biweekly and weekly effectively add payments per year, which matters more than the small compounding gain.

How does the interest rate affect total interest paid?

Interest is charged on the outstanding balance, so a higher rate raises every payment and total cost sharply. On a $25,000 5-year loan, 5% APR costs about $3,307 in interest while 8% costs about $5,415 — a $2,108 difference. Shopping for a lower rate is one of the most effective ways to cut borrowing costs.

What is an amortization schedule and why does it matter?

An amortization schedule lists each payment and shows how much goes to interest versus principal. Early payments are interest-heavy; later ones are principal-heavy. It helps you see exactly when equity builds and how extra payments reduce future interest. Our calculator generates the full schedule automatically.