Loan & Mortgage Calculator
Find the monthly payment, total interest and full amortization schedule for a fixed-rate loan.
Results are provided as is, for general information. Check anything important before relying on it. See the Terms of Use.
About this tool
Uses the standard fixed-rate amortization formula to turn a loan amount, an annual rate and a term into a single monthly payment, then builds the full schedule: for every month it shows the payment, how much goes to interest, how much reduces the balance, and the remaining balance. Early payments are mostly interest; the mix shifts to principal over time. The final row is adjusted so the balance ends on exactly zero rather than a rounding artefact. A 0% rate is treated as the principal split evenly across the term.
How it works
Payment = P × r ÷ (1 − (1 + r)^−n) r = annual rate ÷ 12 ÷ 100, n = years × 12
This is the standard fixed-rate amortization formula. Each month's interest is the remaining balance × r; the rest of the payment reduces the balance, so early payments are mostly interest and later ones mostly principal.
| Question | Working | Answer |
|---|---|---|
| Monthly payment on a $300,000 mortgage at 6.5% over 30 years | r = 0.065 ÷ 12, n = 360 | $1,896.20 a month; $382,636.71 total interest |
| How much of the first payment is interest? | 300,000 × 0.065 ÷ 12 | $1,625.00 interest, $271.20 principal |
| Monthly payment on a $20,000 car loan at 7% over 5 years | r = 0.07 ÷ 12, n = 60 | $396.02 a month; $3,761.48 total interest |
When to use it
Questions
Does this include taxes, insurance or fees?
No. It calculates principal and interest only — the 'P&I' portion of a payment. A real mortgage payment often also includes property tax, homeowners insurance and mortgage insurance held in escrow, which vary by location and lender. Add those separately.
Is the rate compounded monthly?
Yes. The annual rate is divided by 12 to get the monthly rate, and interest each month is charged on the outstanding balance — the standard convention for mortgages and most instalment loans. It does not model daily compounding or a different payment frequency.
Why does the last payment differ slightly from the others?
Rounding every month's interest and principal to the cent leaves a tiny residue over hundreds of payments. Rather than let the balance finish at a few cents above or below zero, the final row pays off the exact remaining balance, so its total can be a cent or two different from the regular payment.
What formula does the payment come from?
The standard fixed-rate amortization formula: payment = P × r / (1 − (1 + r)^−n), with r the monthly rate (the annual rate divided by 12) and n the number of monthly payments. Check it against the tool: a 250,000 loan at 6% over 30 years requires payments of 1,498.88. A 0% rate has no division-by-zero trap here — the tool switches to the simple split, principal divided evenly across the months.
How much does the interest actually add up to?
On typical consumer terms, enough to be worth reading the total-interest line before signing anything. A 250,000 loan at 6% over 30 years costs 289,593.37 in interest on top of the principal — more than the amount borrowed. The same principal at 5% over 5 years (a 10,000-example scaled up) is a different world: short terms are where interest stays small, because fewer months means fewer interest-bearing months.
Why is almost none of my early payment reducing the balance?
Interest every month is charged on the outstanding balance, and early on that balance is at its largest. On the 250,000 loan at 6%, the first payment of 1,498.88 splits into 248.88 principal and 1,250 interest. The monthly rate is 0.5% (6% ÷ 12), so interest accounts for most of the first payment. After 180 payments — halfway through the 30-year term — the balance is still 177,621, about 71% of what you borrowed. The ratio flips steadily from there; by the final payment it is nearly all principal.
Will paying extra each month change the schedule?
Not in this tool — it models the fixed contractual payment only; there is no extra-payment field. What it is good for is seeing the raw material of that decision: every month's interest charge is what an extra payment would skip, and the schedule shows how much of each payment is still going to interest at any point. To approximate an extra-payment plan, compare the interest that would accrue on the extra amount over your remaining term against a shorter-term offer.
Is this the same math my bank used for the quote?
On the principal-and-interest line, yes — the amortization formula is the one every fixed-rate lender uses, so a quoted P&I payment should match to the cent. Divergence usually comes from what sits around it: day-count conventions, rates quoted with points or fees rolled in, or escrow items (taxes, insurance) stacked on top, which this tool does not model. If the P&I figure itself differs, ask which rate and term were actually applied.
Does it model ARMs, interest-only periods or balloon payments?
No — the inputs are one principal, one annual rate, one term, which is the fixed-rate fully-amortizing case. Adjustable rates, interest-only periods and balloon structures all break the constant-payment assumption, so modeling them here would be theater. Many calculators fake it; this one tells you the tool's shape instead, and an amortization of a fixed-rate segment (say, the first 5 fixed years of an ARM) is the closest honest use.
What do the schedule's totals tell me?
The schedule is the loan's whole biography: month by month, the payment, its split into interest and principal, and the remaining balance. The interest column shrinks as the principal column grows — in the 6%/30-year example, payments sum to 539,593.37, of which 289,593.37 is interest. Scan it for the crossover month (where principal first exceeds interest), the point most people find genuinely surprising, and to see exactly where extra principal payments would bite hardest.