How to Calculate Loan Payment

Learn how to calculate your monthly loan payment using the standard loan formula.

Understanding Loan Payments

Loan payments are calculated using the standard loan formula, also known as the annuity formula. This formula takes into account the principal amount, interest rate, and loan term.

Understanding how loan payments work is essential for making informed borrowing decisions. Whether you're taking out a mortgage, auto loan, or personal loan, knowing how your payment is calculated helps you budget effectively.

The Loan Payment Formula

M = P × [r(1+r)^n] / [(1+r)^n - 1]

The standard formula for calculating monthly loan payments

The Formula Explained

Where:

  • M = Monthly payment
  • P = Principal (loan amount)
  • r = Monthly interest rate (annual rate / 12)
  • n = Number of payments (years × 12)

Step-by-Step Example

For a $100,000 loan at 5% annual interest for 30 years:

  1. Principal: P = $100,000
  2. Monthly rate: r = 5% / 12 = 0.4167%
  3. Number of payments: n = 30 × 12 = 360
  4. Monthly payment: M = $536.82

Monthly Payment: $536.82

Total paid over 30 years: $193,255.20

Key Points to Remember

Interest Rate Impact

Higher rates = higher payments

Loan Term Trade-off

Longer term = lower payment, more interest

Payment Structure

Early payments = mostly interest

Related Standards