Loan payment calculator

Estimate the theoretical payment for a fixed-rate amortizing loan.

Your inputs stay in your browser.

Method and assumptions

Method version 1.0.0 · Updated October 2, 2026

Estimate payments

Formula: Payment calculated from principal, monthly rate and number of payments.

Illustrative estimate, excluding insurance and fees.

principal: Loan amount
annualRatePercent: Annual rate (%)
months: Term (months)

Assumes a fixed annual rate, equal monthly payments and monthly periods. Insurance, fees, penalties and eligibility terms are excluded. This estimate is not a loan offer or credit advice.

Calculate with code

These short examples use the same inputs and core calculation as this tool. Adapt validation and formatting to your application.

JavaScript

const principal = 200000, monthlyRate = 0.04 / 12, months = 25 * 12;
const payment = principal * monthlyRate / (1 - (1 + monthlyRate) ** -months);
console.log(payment.toFixed(2)); // monthly payment

TypeScript

const principal = 200000, rate = 0.04 / 12, months = 300;
const payment: number = principal * rate / (1 - (1 + rate) ** -months);
console.log(payment.toFixed(2));

Python

p, r, n = 200000, 0.04 / 12, 25 * 12
print(round(p * r / (1 - (1 + r) ** -n), 2))

Java

double p = 200000, r = 0.04 / 12, n = 300;
System.out.printf("%.2f%n", p * r / (1 - Math.pow(1 + r, -n)));

double p = 200000, r = 0.04 / 12, n = 300;
Console.WriteLine(Math.Round(p * r / (1 - Math.Pow(1 + r, -n)), 2));