Loan Calculators
Loan Interest Calculator
See exactly how much interest a loan costs over its life and how the interest share of each payment falls over time.
Monthly payment
$497.70
- Total interest
- $3,890
- Total repaid
- $23,890
- Payoff time
- 48 months
- Interest
- Principal
Repayment schedule — yearly
| Year | Interest paid | Principal paid | Balance remaining |
|---|---|---|---|
| 1 | $1,624 | $4,349 | $15,651 |
| 2 | $1,216 | $4,757 | $10,894 |
| 3 | $769 | $5,203 | $5,691 |
| 4 | $281 | $5,691 | $0 |
How this calculator works
M = P × r ÷ (1 − (1 + r)^−n)
- P
- the amount borrowed, including any financed fee
- r
- the monthly interest rate
- n
- the number of monthly payments
Example calculation
Illustrative example — not advice
Worked example — the loan interest calculator as it loads, using the default figures below.
- 01Enter loan amount: $20,000.
- 02Enter interest rate: 9%.
- 03Enter term: 4 years.
- 04Enter extra monthly payment: $0.
- 05Read the monthly payment from the results panel: $497.70.
Monthly payment: $497.70. Total interest: $3,890. Total repaid: $23,890. Payoff time: 48 months.
These figures come straight from the calculator above running on the values listed, so you can retype them and confirm every number yourself. Change any input and the results update immediately. Illustrative only — not a quote, offer or recommendation.
Important considerations
- Early repayment charges are not modelled — check your agreement before overpaying.
- Fees and insurance products added by the lender change the true cost.
Related calculators
- Loan Payment CalculatorMonthly repayment, total interest and the effect of paying extra each month.
- Simple Interest CalculatorInterest charged on the original amount only.
- APR CalculatorThe true annualised cost of a loan once fees are included.
- Amortization CalculatorFull interest and principal schedule for any loan.
- Personal Loan CalculatorRepayments and total interest on an unsecured personal loan.
- Student Loan CalculatorStudent loan repayments, interest and payoff timing.
Terms used here
Frequently asked questions
Does paying extra each month help much?
Yes. Extra payments reduce the balance directly, so all future interest is charged on a smaller amount and the loan ends earlier.
Disclaimer
Legamoney calculators are educational tools. Results are estimates based on the figures you enter and do not constitute financial, tax or legal advice.
Last reviewed 2026-08-01