Loan Calculator
Calculate the monthly payment, total interest, and payoff date for any fixed-rate loan — personal loan, student loan refinance, boat loan, or any other installment debt. See the full amortization schedule and how an extra monthly payment changes the numbers.
Monthly Payment
$579.98Total Interest
$4,799Payoff Date
Aug 203160 payments
| Detail | Value |
|---|---|
| Loan Amount | $30,000 |
| Scheduled Payment | $579.98 |
| Number of Payments | 60 |
| Total Interest | $4,799 |
| Total Paid | $34,799 |
| Year | Interest | Principal | Balance |
|---|---|---|---|
| 1 | $1,656 | $5,304 | $24,696 |
| 2 | $1,329 | $5,631 | $19,065 |
| 3 | $981 | $5,979 | $13,086 |
| 4 | $613 | $6,347 | $6,739 |
| 5 | $221 | $6,739 | $0 |
Calculations use the standard fixed-rate amortization formula. Your actual payment depends on your lender's exact APR, fees, and rounding conventions — treat this as an estimate.
Edit inputs ↑How the amortization formula works
A fixed-rate installment loan uses the same payment every period, but the SPLIT between interest and principal changes every time. Each period's interest = current balance × (APR ÷ 12). Whatever's left of the fixed payment goes to principal, which shrinks the balance for next period's interest calculation. That's why the same $579.98 payment on the $30,000/6%/60-month fixture above is mostly interest in month 1 (interest ≈ $150, principal ≈ $430) and almost entirely principal by month 60 (interest ≈ $3, principal ≈ $577) — the figures above update live from whatever you enter.
This is standard fixed-rate amortization math with no tax-year dependency — the same formula applies whether you're financing a personal loan, a boat, tuition, or any other installment debt. For a home loan specifically (with property tax and insurance folded in), use the Mortgage Calculator; for a vehicle (with sales tax and trade-in), use the Car Loan Calculator.
Term in months vs. years — same math, different unit
Loan terms are quoted in years for a mortgage or auto loan (e.g. "5 years") and often in months for a personal loan or buy-now-pay-later plan (e.g. "36 months"). Both feed the same n in the payment formula — 5 years and 60 months produce an identical schedule. Use the months/years toggle above to match how your lender quoted the term without doing the multiplication yourself.
Frequently asked questions
How do you calculate a loan payment?
Every fixed-rate, fully-amortizing loan uses the same formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the amount borrowed, r is the monthly interest rate (APR ÷ 12), and n is the total number of monthly payments. Example: a $30,000 loan at 6% APR over 60 months → r = 0.06/12 = 0.005, n = 60, M = $579.98/month. At 0% APR the formula simplifies to P ÷ n — an even split with no interest.
What's the difference between the interest rate and the APR?
The interest rate is the pure cost of borrowing applied to your balance each period. The APR (annual percentage rate) folds in certain lender fees and points, spreading them over the loan term as an effective rate — so the APR is usually slightly higher than the quoted interest rate. Federal Truth in Lending Act rules require lenders to disclose the APR so loans are comparable across lenders. This calculator treats your entered rate as the APR that drives the monthly payment; if a lender quotes you a lower 'note rate' plus separate points or fees, use the APR for an apples-to-apples comparison.
Why does more of my payment go to interest at the start?
Interest is charged only on the remaining balance each period (balance × monthly rate). Early on, the balance is largest, so the interest slice is largest and the principal slice is smallest. As the balance shrinks, less of each payment is needed for interest, so more goes to principal — the schedule below shows this shift year by year.
How much does an extra monthly payment actually save?
Every extra dollar goes straight to principal, which reduces the balance every future period is charged interest on — so extra payments made early in the loan compound the most. Check the box above to add a recurring extra payment and see the new payoff date and total interest; for a side-by-side comparison against paying on schedule, plus one-time lump-sum payments, use the Amortization Calculator.
Sources
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