COMPARE YOUR OPTIONS
15 vs. 30-year mortgage calculator
Put two repayment plans side by side. Use the same loan amount and enter a separate rate for each option to see the monthly commitment and lifetime interest.
Illustrative example
Difference in total interest
$127,282.33
Option A has less total interest.
| Plan | Option A | Option B |
|---|---|---|
| Monthly payment | $1,976.98 | $1,342.05 |
| Payoff time | 15 years | 30 years |
| Total interest | $105,857.13 | $233,139.46 |
| Total paid | $355,857.13 | $483,139.46 |
A smaller payment or a shorter loan?
How to compare two mortgage terms
Enter the amount you plan to borrow, then the term and annual rate for each option. The defaults compare 15 and 30 years at the same illustrative rate so you can isolate the effect of the term. Replace them with the rates in your actual quotes.
Why the shorter term changes the payment
At the same positive interest rate and loan amount, a shorter term spreads principal repayment across fewer months. That increases the monthly payment but reduces total interest. Different quoted rates can change the size of that tradeoff; the calculator uses each rate separately.
What else should I compare?
Look at closing costs, ongoing housing expenses and the payment you can sustain. This comparison includes principal and interest only. It does not decide which loan is affordable for you or account for what you might earn by investing a difference in payments.
How these numbers are calculated
We use monthly amortization: M = P × r / (1 − (1 + r)−n), where P is the balance, r is the annual interest rate divided by 1,200 and n is the number of monthly payments. Here, the rate input is the nominal interest rate, not an APR that includes fees. At zero interest, M = P / n.
Interest is calculated on the opening balance each month. Payments arrive at month end; any extra payment reduces principal immediately. Rates stay fixed, payments are never missed and the final payment is capped at the remaining balance plus interest. Calculations retain precision internally; displayed amounts and CSV rows are rounded to cents.
Estimates exclude taxes, insurance, closing costs and early-repayment charges. Lender rounding, daily interest or different compounding conventions can produce different results. These tools are for exploring scenarios, not personalized financial advice.
Sources and verification
The explanations were checked against the following US consumer resources on September 6, 2026. Local rules and your loan agreement may differ.
Built with AI assistance. The calculation model is checked with automated reference and edge-case tests; no independent financial adviser review is claimed. Found an issue? Report a calculation or content error.
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