15-Year Mortgage Calculator
A 15-year mortgage costs more monthly but saves tens of thousands in interest and builds equity fast. This shows the real trade-off side by side.
What does this tool do?
15-Year Mortgage Calculator computes the result directly in your browser — A 15-year mortgage costs more monthly but saves tens of thousands in interest and builds equity fast. This shows the real trade-off side by side. Nothing you enter is uploaded or stored.
The trade-off: a 15-year mortgage trades a higher monthly payment for a much lower rate and half the interest runway. On a $320,000 loan at example 5.5% vs 6.5%, the 15-year pays about $200,000 less in interest. Consider it if: your cash flow supports the higher payment and you want to retire the mortgage by mid-career. Alternative: a 30-year with extra principal payments gives flexibility (pay the 15-year amount when you can, minimum when you can't) with most of the same savings.
How to verify this calculation
The page subtracts the down payment from the home price and floors the loan amount at zero. For a positive monthly rate r, payment is P × r ÷ [1 − (1 + r)^−n], using 180 months for the 15-year option and 360 for the comparison. At zero interest it uses P ÷ n. Check a hypothetical $200,000 home with $20,000 down and both rates set to zero: P = $180,000; payments are $180,000 ÷ 180 = $1,000 and $180,000 ÷ 360 = $500. Each schedule repays $180,000, so both interest totals and interest savings are zero; the monthly difference is $500.
Compare the same loan amount and separate rates
The comparison holds the loan amount constant but accepts separate rates for the two terms. Changing the down payment changes both schedules, while changing only the 15-year rate changes only that option's modeled payment and interest. Interest is calculated as payment multiplied by the number of months, minus the original principal. It assumes the loan runs to its scheduled end, without extra payments or refinancing. The displayed monthly amount contains principal and interest only; it cannot represent costs for which the page has no inputs. Use nonnegative rates and a down payment no larger than the price for a meaningful comparison.
FAQ
Is a 15-year mortgage worth it?
It saves a large amount of interest and builds equity faster, but the monthly payment is significantly higher. If the higher payment is comfortable, it's usually a strong choice for long-term savings.
How much more is the monthly payment?
On a $320,000 loan at example rates, the 15-year runs about $500-$700 more per month than the 30-year — but saves roughly $200,000 in interest and pays off 15 years sooner.
What if I can't always afford the 15-year payment?
A 30-year mortgage with automatic extra principal gives you the option to pay down fast when cash is good and drop to the minimum when it isn't — flexible and nearly as effective.
Figures are editable example defaults for modeling, not quotes or advice. Financial, tax, and medical outcomes vary with your situation — verify with a qualified professional (CFP, CPA, tax advisor, or veterinarian).