Loan Amortization Calculator
Get the monthly payment, total interest, and balance schedule for any fixed-rate loan. Useful for mortgages, auto loans, and personal loans — runs in your browser with no signup.
Monthly payment
$1,580
Total paid over life of loan
$568,861
Total interest paid
$318,861
Interest paid per $1 borrowed
1.28
Total months
360
Remaining Balance Over Time
How to read your result
The 'Monthly payment' is what you owe every month for the entire term — fixed-rate amortization holds it constant. It's the headline figure to budget against.
'Total interest paid' is what you'll hand over to the lender beyond the principal. On a 30-year mortgage at typical rates, total interest often equals or exceeds the principal — borrowing $250,000 at 6.5% costs you roughly $320,000 in interest on top.
'Interest paid per $1 borrowed' converts that into a quick ratio. At 6.5% over 30 years, every $1 borrowed costs roughly $1.27 in interest. Compare across rate/term combinations: a 15-year at the same rate cuts that ratio to about $0.55. Half the term, less than half the lifetime interest.
The chart shows three lines simultaneously. Watch how slowly the principal line climbs in early years — that's because most of each early payment goes to interest, not principal. The crossover point where principal-paid catches up to interest-paid is typically year 18–22 on a 30-year loan.
When to use this tool
- ›Comparing 15-year vs. 30-year mortgage terms at the same rate. Lower-rate vs. higher-rate at the same term.
- ›Calculating the total cost of an auto loan at the dealer's offered rate vs. a credit-union rate.
- ›Sanity-checking a personal-loan offer. Some lenders quote a low rate but stretch the term to make total interest much higher.
- ›Visualizing how front-loaded interest is. Early payments are 70%+ interest on a fresh 30-year mortgage; the chart makes the 'why does my balance barely move' phenomenon concrete.
Methodology
The monthly payment formula is the standard fixed-rate amortization equation: P × r / (1 − (1 + r)^−n), where P = principal, r = monthly rate, n = total number of payments. At a 0% rate the formula simplifies to P / n.
All math is in nominal dollars at the rate you enter — no inflation adjustment, no tax-deduction adjustment. For an inflation-aware view, convert the rate to a real rate using the Fisher equation (see /tools/inflation-real-return/).
We do not model PMI, escrow, property taxes, or homeowner's insurance for mortgages — those are separate line items added on top of the principal-and-interest payment. We also do not model points, origination fees, or prepayment penalties.
Limits we acknowledge: this calculator assumes a fixed rate for the entire term. ARM (adjustable-rate) loans, balloon loans, and graduated-payment loans need different math. For ARMs specifically, this calculator is accurate for the initial fixed period only.
Site-wide methodology framework: /methodology/ · Pre-publication standards: /editorial-standards/
FAQ
Why does my mortgage statement show different numbers than this calculator?
Three common reasons: (1) your statement includes PMI, escrow, and insurance — this calculator shows principal-and-interest only; (2) your loan may have a slightly different day-count convention (actual/360 vs. 30/360) that the calculator doesn't model; (3) if you've made extra principal payments, the schedule shifts. The calculator gives the as-if-you-pay-exactly-the-monthly-amount-every-month projection.
Is a 15-year really better than a 30-year?
Cheaper in total interest, yes — usually 60–65% less. But the monthly payment is higher (typically 30–50% more), which constrains other parts of your budget. The trade-off depends on whether you have higher-return uses for the cash freed up by the lower 30-year payment (retirement contributions, business investment, etc.). The calculator shows you the cost difference; the right answer depends on your alternative uses.
What rate should I plug in?
For mortgages, use the rate you've actually been offered (or the current average for your credit profile from a rate-tracker). For auto loans, the dealer rate vs. a credit-union pre-approval rate often differ by 1–3 points. For personal loans, rates vary 8–25% depending on credit. The calculator's default 6.5% reflects mid-2026 30-year mortgage rates — adjust to your actual offer.
How much does a 1-point rate difference matter?
A lot, especially over long terms. On a $300,000 30-year loan, the difference between 6% and 7% is roughly $200/month and $72,000 in lifetime interest. On a 15-year, the same 1-point difference is roughly $150/month and $26,000 in lifetime interest. Shopping for the lowest rate matters more on longer terms.
Why is the early-year balance line so flat?
Because amortization is interest-heavy at the start. Each monthly payment is split between interest (calculated on remaining balance) and principal (what's left of the payment). On a fresh 30-year loan, the first payment is roughly 70–80% interest, 20–30% principal. By the last year, that ratio reverses. The calculator's chart visualizes that — the principal line climbs slowly for years, then accelerates.
Does this calculator work for 'pay extra principal' scenarios?
Not directly — it shows the standard schedule with no extra payments. For a quick estimate of extra-payment impact: every $100/month added to a 30-year mortgage at 6.5% saves roughly 5–7 years and tens of thousands in interest. For exact numbers, use the calculator at the original schedule, then run again with a higher monthly payment by adjusting term shorter.