Loan Payment Calculator
Estimate your monthly loan payment, total interest, and total cost from the loan amount, annual rate, and term in years.
What this loan payment calculator does
This calculator estimates the fixed monthly payment on an amortizing loan — the kind used for most mortgages, auto loans, personal loans, and student loans. With an amortizing loan you pay the same amount every month, and each payment is split between interest (charged on whatever principal is still outstanding) and principal (which reduces the balance). Early payments are mostly interest; later payments are mostly principal. By the final payment, the balance reaches exactly zero.
Alongside the monthly payment, the tool shows the total amount paid across the life of the loan and the total interest — the difference between what you borrow and what you ultimately hand back. That second number is usually the more revealing one, and it is the one loan advertising tends to leave out.
How to use it
- Loan amount — the principal you actually borrow, after any down payment or trade-in.
- Annual interest rate — the nominal annual rate your lender quoted, entered as a percentage (for example, 6.5 for 6.5%). If you were quoted an APR that folds in fees, using it here gives you a closer estimate of true cost.
- Loan term — the repayment period in years. Enter 0.5 for six months, 30 for a thirty-year mortgage.
Results update as you type. Try changing one field at a time: dropping the rate by a point, or shortening the term by a year, shows immediately how much interest that decision saves. Rates vary by borrower, credit profile, and lender, so use a rate you have actually been quoted rather than a national average.
The amortization formula
The standard formula for a fixed monthly payment is:
M = P × i / (1 − (1 + i)−n)
- M = the monthly payment
- P = the principal (loan amount)
- i = the monthly interest rate, which is the annual rate divided by 100 and then by 12
- n = the total number of monthly payments (years × 12)
The formula assumes monthly compounding, which is how the overwhelming majority of consumer loans are quoted. When the interest rate is 0%, the formula divides by zero, so the calculator falls back to the correct special case: M = P / n, an equal split of the principal across every payment. Empty, negative, or non-numeric entries are treated as zero, so you will never see NaN or Infinity in the results.
Total paid is simply M × n, and total interest is (M × n) − P. Because the monthly payment is rounded to the cent in practice, a real lender's final payment is often a few cents different from the others; this estimate does not model that rounding.
Worked example
Suppose you borrow $25,000 at 6.5% over 5 years. The monthly rate is 0.065 / 12 = 0.00541667, and the number of payments is 5 × 12 = 60. Plugging those in:
M = 25,000 × 0.00541667 / (1 − 1.00541667−60) = $489.15 per month.
Over 60 payments that comes to $29,349.00, meaning $4,349.00 of it is interest — roughly 15% of everything you pay. Stretch the same loan to 7 years and the monthly payment drops to about $372, but total interest climbs past $6,200. That trade-off is the single most useful thing this calculator makes visible: a longer term buys a smaller monthly payment with a larger total bill.
What it does not include
This is a principal-and-interest figure. Mortgage lenders typically escrow property taxes, homeowners insurance, and private mortgage insurance on top of it, which can add materially to the amount you send each month. Auto loans may bundle in fees or gap insurance. Some loans carry origination fees deducted from the amount you receive, or prepayment penalties that change the calculus if you plan to pay early. Ask your lender for the full disclosure before signing — the CFPB publishes guides on how to read them.
This tool runs entirely in your browser. Nothing you enter is transmitted, stored, or logged anywhere. It is an estimate for planning purposes and not financial advice.