Loan & mortgage calculator
Monthly payment, total interest and total cost.
How to use the loan & mortgage calculator
- Enter the loan amount — the principal you'd actually borrow. For a mortgage, that's the purchase price minus your down payment.
- Enter the annual interest rate as a percentage, e.g.
6.5. Use the quoted interest rate, not an APR that bundles fees. - Set the term in years — 30 or 15 are typical for mortgages, 5 or 6 for car loans. The tool converts it to monthly payments internally.
- Read the three outputs: monthly payment (principal + interest), total interest over the life of the loan, and total paid. The defaults — $250,000 at 6.5% for 30 years — give $1,580.17 a month and $318,861 in interest.
- Everything updates live, so change one number at a time to compare scenarios: a different rate, a shorter term, a bigger down payment.
Common uses
- Estimate a mortgage payment while house-hunting, and watch how the monthly cost moves as you adjust price or down payment.
- Compare terms honestly: $250,000 at 6.5% costs about $318,861 in interest over 30 years but only ~$142,000 over 15 — for a payment that rises from $1,580 to $2,178.
- See what rate shopping is worth — on that same loan, dropping from 6.5% to 6.0% saves about $81 a month and roughly $29,000 overall.
- Price a car loan: $25,000 at 7.9% over 5 years is $505.71 a month and about $5,343 in interest.
- Sanity-check a personal or student loan offer: multiply out what "only $X a month" really costs in total.
Tips & limitations
- The figures are principal and interest only. A real mortgage payment usually adds property tax, homeowners insurance, possibly PMI and HOA fees — so budget above the number shown.
- It assumes a fixed rate compounding monthly for the whole term, the standard US convention. Adjustable-rate mortgages, interest-only periods and loans compounded differently won't match exactly.
- Enter the nominal interest rate, not the APR — APR folds in fees, so using it here overstates the monthly payment.
- There's no amortization schedule or extra-payment modeling. Early payments are mostly interest, and paying extra principal cuts total interest substantially — this tool can't show by how much.
- Amounts display in US dollars, but the math is currency-agnostic — read the results in whatever currency you entered.
How it's built & why it's safe
This is the standard amortization (annuity) formula computed live in your browser: monthly payment M = P·i / (1 − (1+i)^−n), where P is the amount borrowed, i the annual rate divided by 12, and n the term in months. Total paid is M × n, total interest the difference from the principal, and a 0% rate falls back to a straight division. Results are formatted as currency with toLocaleString. Nothing you type is stored or sent anywhere — amounts and rates stay on your device. These are estimates, not a lending offer.
Related tools: Percentage Calculator · Discount & Tax Calculator · Bill Splitter & Tip Calculator
Further reading: Why Toolkit runs entirely in your browser (and why that matters)
Frequently asked questions
How is the monthly payment calculated?
With the standard amortizing-loan formula M = P x i / (1 - (1 + i)^-n), where P is the principal, i the monthly rate (annual / 12) and n the number of monthly payments — the same math lenders use for fixed-rate loans.
Why is the total interest sometimes more than the loan itself?
Long terms do that: interest accrues on the outstanding balance every month for decades, and early payments barely dent the principal. At 6.5% over 30 years, a $250,000 loan accrues about $318,861 in interest — shortening the term is the most direct fix.
Does it include taxes, insurance or PMI?
No — the payment shown is principal and interest only. Property tax, homeowners insurance, mortgage insurance and HOA dues are collected on top (often via escrow) and vary by location, so budget them separately.
Should I enter the interest rate or the APR?
The interest rate. APR folds one-time fees into a comparison number — useful for ranking offers, wrong for computing payments. Entering APR here overstates what you'd pay each month.
Can it model extra payments or an amortization schedule?
Not in this version — it computes the level payment for the full term. Extra principal payments shorten the loan and cut total interest, often dramatically, but you'd need an amortization-schedule tool to see the month-by-month effect.
What happens at 0% interest?
The formula would divide by zero, so the calculator switches to a straight split: principal divided by the number of months, with zero total interest. Handy for promotional 0% financing.
Is my financial information saved anywhere?
No. The calculation runs entirely in your browser — no server, no account, no storage. Reload the page and the fields return to the example defaults.