Mortgage Calculator: monthly payment and amortization
Free online mortgage calculator. Estimate your monthly payment, total interest, and a full amortization schedule for any home loan. Add an optional extra monthly payment to see how much faster you'd be debt-free — all in your browser.
What you'll use this for
Home shopping
See if a listing fits your monthly budget at today’s rates.
Refinance vs keep
Compare a new rate against your current mortgage payoff.
Extra payments
See how much faster you finish by adding $100 / $200 per month.
Savings planning
Use total-interest figures to budget years ahead.
How to use the mortgage calculator
Enter the loan basics
Home price, down payment, rate, and term in years.
Optionally add extras
Extra monthly payment shaves years off the back end.
Read the schedule
Year-by-year principal vs interest breakdown.
Frequently asked questions
No — this is principal & interest only. Property tax, homeowners insurance, HOA, and PMI are property-specific and aren’t modeled here.
Standard amortization: payment = P × r / (1 − (1+r)⁻ⁿ), where P is the loan amount, r is the monthly rate (annual ÷ 12), and n is the number of months.
Penny-accurate to one cent per month relative to a US lender’s standard amortization table. Real lenders sometimes round differently in the final months.
Each extra dollar goes straight to principal, lowering the balance the next month’s interest is calculated on. Even small extras compound dramatically over a 30-year loan.
About mortgage math
A mortgage is an amortizing loan: each monthly payment is split between interest (computed on the remaining balance) and principal (which reduces the balance). Early in the loan, most of every payment is interest; later, almost all of it is principal.
The formula
M = P × r × (1+r)ⁿ / ((1+r)ⁿ − 1)
P = loan amount
r = annual rate / 12
n = total monthsWhy extras matter so much
On a $300K loan at 6.5% / 30 years, an extra $200/mo cuts roughly 7 years and tens of thousands of dollars in interest off the back end. The earlier you add the extra, the bigger the impact.