Loan Calculator — monthly payment & total interest

Monthly payment M = P·r(1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P is the amount, r the monthly rate, and n the number of months. A 100,000 loan at 5% for 30 years costs 536.82 per month.

Estimates for information only — not financial advice. Actual terms, fees, and rates depend on your provider.

Enter your own loan amount, annual interest rate, and term — this tool has no lender data and makes no offers. It computes the standard amortized payment, total paid, and total interest, instantly and privately in your browser.

Formula & methodology

Standard amortization: M = P·r(1+r)ⁿ ÷ ((1+r)ⁿ − 1) with monthly rate r = annual ÷ 12 ÷ 100 and n = years × 12. A zero-rate loan degenerates to M = P ÷ n. Rounding: the payment is rounded half-up to 2 decimals first, then totals are derived from the rounded payment — matching how installments are actually charged.

Worked example

100,000 at 5% for 30 years → monthly 536.82, total paid 193,255.20, total interest 93,255.20. Notice interest almost equals the principal — term length dominates total cost.

Limits

Real offers add fees, insurance, and different day-count conventions; variable rates change everything after the fixed period. Results are estimates, not an offer or financial advice.

Frequently asked questions

Why does my bank quote a slightly different payment?

Banks add processing fees and insurance and may use a different rounding or day-count convention. The amortization core is the same formula used here.

How can I cut total interest fastest?

Shorten the term. In the example above, moving from 30 to 15 years raises the payment but cuts total interest by more than half.