Loan Calculator
Work out monthly payments, total interest and the full repayment schedule.
Loan Calculator
Work out monthly payments, total interest and the full repayment schedule.
Starts in your browser. Instructions are below.
How to use Loan Calculator
- 01Enter the amount borrowed, the annual interest rate and the term in years.
- 02Read your monthly payment and the total interest you will pay over the term.
- 03Open the schedule to see how each payment splits between interest and principal.
About Loan Calculator
A repayment loan uses the same payment every month, but the split changes: early payments are mostly interest because the balance is high, and later ones are mostly principal. That is why overpaying early saves disproportionately more interest.
Total cost is the part people underestimate. Extending an auto, personal or student loan lowers the monthly payment but adds interest , the schedule here shows both numbers side by side so the trade-off is visible.
Worked example: a $25,000 loan at 7.5%
Borrow $25,000 at 7.5% for 5 years and the monthly payment is $500.95. You repay $30,056.92 in total, so the loan costs $5,056.92 in interest. Shorten the term to 3 years and the payment rises to $777.66, but interest falls to $2,995.60.
| Rate (5-year term) | Monthly payment | Total interest |
|---|---|---|
| 5% | $471.78 | $3,306.85 |
| 7.5% | $500.95 | $5,056.92 |
| 10% | $531.18 | $6,870.57 |
| 15% | $594.75 | $10,684.90 |
Going from 5% to 15% raises the payment by only $123 a month but more than triples the interest. That is why a small rate difference matters more on longer loans.
The formula
The payment uses the standard amortization formula: M = P × r ÷ (1 − (1 + r)^−n), where P is the amount borrowed, r is the yearly rate divided by 12 and n is the number of monthly payments. Each month, interest is charged on the remaining balance and the rest of the payment reduces that balance.
Common mistakes
- Comparing payments instead of total interest. A longer term always looks cheaper per month.
- Entering the APR from an ad without fees. If the lender charges an origination fee, the true cost is higher than this result.
- Forgetting that extra payments only help if the lender applies them to principal. Ask, or label the payment as principal-only.
Frequently asked questions
- Which loans can I calculate?
- Any standard fixed-rate installment loan, including auto, personal and student loans.
- What does an amortization schedule show?
- Each payment broken into interest, principal and the remaining balance.
- Can I model overpayments?
- Yes, add a monthly overpayment to see how much interest and time it saves.
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