Countwell

Loan Payment Calculator

See exactly what a fixed-rate loan will cost you each month, and how much of the money goes to interest.

Last updated: August 5, 2026

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Monthly payment
Total interest
Total cost over term

How loan payments work

Borrowing money costs money. Each monthly payment is split between repaying what you borrowed (principal) and paying the lender for the privilege (interest). The longer you take to repay, the more months you pay interest, so the total cost rises even though each payment feels smaller.

This calculator works for any fixed-rate loan where the rate does not change during the term. The standard formula produces a level monthly payment that fully pays the loan off by the end of the term.

The formula

Monthly payment = L × r(1 + r)^n ÷ ((1 + r)^n − 1)
  • L — loan amount
  • r — monthly interest rate (annual ÷ 12, as a decimal)
  • n — total number of monthly payments

Worked example

You borrow $20,000 at 8% for 5 years.

Monthly payment ≈ $405.53. Total repaid ≈ $24,332, of which $4,332 is interest.

Now try the same amount at 8% over 7 years. The payment drops, but the total interest jumps to roughly $6,200 — the real cost of stretching a loan out.

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Frequently asked questions

Can I pay a loan off early?

Usually, but check your agreement. Some lenders charge a prepayment fee, and paying early reduces future interest. This calculator shows the standard schedule, not the effect of extra payments.

Does this include fees?

No, only interest on the loan amount. Origination fees, annual charges or late fees would be added on top of these numbers.

What if the rate is variable?

The figure is only an estimate, since the payment changes whenever the rate changes. Use the current rate to get a sense of the starting payment.

This calculator gives an estimate only and is not financial advice. Your lender sets the actual rate, fees and payment terms.