Loan / Mortgage Calculator
Compute monthly payments and view the full amortization schedule.
| Month | Payment | Principal | Interest | Balance |
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Formula:
- Monthly payment:
PMT = P × r / (1 − (1 + r)−n)wherer = annualRate / 12andn = years × 12. - When rate is 0%:
PMT = P / n.
How loan amortization works
The fixed-payment structure
A standard amortizing loan has a constant monthly payment. Each payment is split into interest (the bank's cut) and principal (reduces your balance). Early in the loan, most of the payment goes to interest. As the balance shrinks, more of each payment goes to principal. The full schedule is shown when you expand the table below the chart.
Why extra payments save so much
Every extra dollar you pay goes 100% to principal — there is no interest on an extra payment. That reduces the balance on which the next month's interest is calculated, which compounds across the remaining term. Even $100/month extra on a 30-year mortgage can cut several years off the payoff and save tens of thousands in interest.
APR vs. interest rate
The interest rate is the cost of borrowing the principal. The APR (annual percentage rate) includes the interest rate plus certain fees — points, origination, mortgage insurance. APR is usually a slightly higher number and is the better figure for comparing loan offers.
Worked examples
Example 1: $200,000 mortgage at 6.5% for 30 years
Enter principal = 200000, annualRate = 6.5, years = 30, extra = 0. Result: monthly payment $1,264.14, total interest $255,089, paid off in 30 years.
Example 2: Same loan with $200/month extra
Same inputs but extra = 200. The loan is paid off in about 20 years 10 months — roughly 9 years 2 months earlier — and the total interest drops by about $90,000.
Example 3: 15-year vs 30-year at the same rate
A 15-year mortgage at 6% has a higher monthly payment (~$844 per $100k borrowed, vs. ~$600 for the 30-year version) but total interest is roughly half — about $52k instead of $116k per $100k — because the principal is paid off twice as fast. This calculator lets you compare both at the same rate.
Related tools
The Loan Calculator is the right tool for any fixed-rate amortising loan: mortgages, auto loans, personal loans, student loans, and home-equity lines (when the rate is fixed). Three common follow-up questions:
- "Should I make extra payments?" The Extra Monthly Payment input shows the impact directly. For most fixed-rate mortgages, even $100-200/month extra saves tens of thousands in interest and years off the term.
- "Should I take a 15-year or 30-year mortgage?" Use this calculator at the same rate for both terms and compare total interest. The 15-year wins on total cost; the 30-year wins on monthly cash flow.
- "What's my effective rate after fees?" This calculator shows the nominal rate, not APR. For APR-style comparisons, factor points and origination fees into the principal and re-run.
For a savings or investment goal (the opposite of a loan), use the Compound Interest Calculator. For a project with mixed inflows and outflows, use the NPV / IRR Calculator.
Frequently asked questions
Does this include property taxes or insurance?
No. The result is principal and interest only (P&I). A real monthly mortgage payment usually also includes property taxes, homeowner's insurance, and possibly PMI or HOA fees — collected via an escrow account. Add those separately to your budget.
What does "Payoff Time" mean when I enter an extra payment?
It's the actual number of months until the balance hits zero, given your extra payment. The original term (e.g. 30 years) is the contracted payoff time; with extras, you'll finish sooner.
Is this calculator accurate for adjustable-rate mortgages?
No. This calculator assumes a fixed rate for the entire term. For an ARM, the payment will change at each rate reset — you'll need to recompute at each reset using the new rate and the remaining term and balance.