How to Calculate Your Loan Monthly Payment (Step-by-Step Guide)

Whether you’re planning a car loan, personal loan, or mortgage, knowing your monthly payment helps you budget and compare offers. This guide walks you through it step by step—no math degree required.

Step 1: Gather your three numbers

Every fixed-rate loan payment depends on three things:

• Principal (P) — the amount you borrow
• Annual interest rate (r) — expressed as a percentage (e.g. 6%)
• Loan term in months (n) — how long you’ll repay (e.g. 36 months, or 360 for a 30-year mortgage)

Your lender will quote these. If you have a down payment or trade-in, subtract that from the purchase price to get the principal you actually finance.

Step 2: Use a calculator or the formula

The easiest way is to use a free loan calculator. Enter your amount, rate, and term—you’ll get the monthly payment instantly. No signup required.

If you prefer the math, the standard formula for a fixed monthly payment is:

M = P × [r(1+r)^n] / [(1+r)^n − 1]

Where r is the monthly rate (annual rate ÷ 12, as a decimal). For example, 6% annual becomes 0.005 monthly. This is the same formula banks use for amortizing loans.

Step 3: Worked example

Say you borrow $10,000 at 6% for 36 months.

• Principal: $10,000
• Monthly rate: 6% ÷ 12 = 0.5% (0.005)
• Term: 36 months

Plugging into the formula (or our loan payment example page), your monthly payment is about $304. Over 36 months you pay roughly $10,952 total—$952 of that is interest.

Try it yourself: use our loan calculator and enter 10000, 6, and 36. You’ll see the same result.

Step 4: Compare scenarios

Changing any number changes your payment. A longer term usually means a lower monthly payment but more total interest. A higher rate raises both the payment and total cost.

Example: that $10,000 loan at 6%. At 24 months, the payment jumps to about $443—but total interest drops to around $632. At 48 months, the payment falls to about $235—but total interest rises to about $1,280.

Use our loan calculator with interest breakdown to see year-by-year how much goes to principal vs. interest.

Tips before you borrow

• Compare APRs, not just monthly payments—fees can hide in the fine print.
• Run different terms (e.g. 48 vs. 60 months) to see the trade-off between payment size and total interest.
• For car loans, check how much car loan you can afford before you shop.
• For home loans, try our mortgage calculator or 30-year mortgage calculator.

Frequently asked questions

What is the formula for monthly loan payment?

For fixed-rate amortizing loans, the standard formula is M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is principal, r is the monthly interest rate (annual ÷ 12), and n is the number of months. Our loan calculator does this for you.

How do I calculate a car loan payment?

Use the same formula or our car loan calculator. Enter the amount you’re financing, your quoted APR, and the term in months (e.g. 60 for five years).

Does a longer loan term mean a lower payment?

Yes. Spreading the principal over more months lowers the monthly payment. But you usually pay more total interest over the life of the loan. Run both scenarios in a calculator to compare.

What’s the difference between interest rate and APR?

The interest rate is the cost of borrowing. APR (annual percentage rate) includes fees and gives a fuller picture of cost. Always compare APRs when shopping lenders.