Mortgage Amortization Calculator
Adjust the inputs below. Results update as you type.
How it works
Each payment: interest = balance × monthly rate; principal = payment − interest; new balance = balance − principal. Early payments are mostly interest; late payments mostly principal (front-loaded interest structure). Extra principal payments applied early in the loan save the most interest because they eliminate years of compounding. Bi-weekly payments (26 per year) make one extra monthly payment annually.
Input guidance
- Use realistic rates from lender or provider quotes instead of headline averages.
- Model conservative, baseline, and optimistic scenarios before deciding.
- Include recurring real-world costs (fees, taxes, insurance, maintenance) where relevant.
The formula
Each month: interest = balance × monthly rate, principal = payment − interest, new balance = balance − principal. The schedule lists every payment until the balance hits zero.
Worked example
On a $200,000 loan at 5% for 30 years (payment ≈ $1,074), month one is $833 interest and $241 principal; by the final year nearly the whole payment is principal.
More examples to test
- Conservative case: use a higher interest rate and lower growth assumptions to stress-test affordability.
- Optimistic case: use a lower rate with stable income assumptions to compare upside potential.
How to interpret results
Treat this as a planning model, not a final approval tool. Compare at least two scenarios and focus on total-cost and cash-flow trade-offs.
When this can be inaccurate
Results can diverge due to fees, changing rates, tax rules, lender policies, and behavior changes that simplified models cannot fully capture.
Change history
- July 2026: Quality-reviewed for publication with formula checks and explanatory copy updates.
Site-wide corrections also appear on the corrections log.
Frequently asked questions
What does the amortization schedule show?+
How each payment splits between interest and principal over the life of the loan, and the remaining balance after every payment.
When do I cross over to mostly principal?+
On a 30-year loan it takes many years. The crossover point comes sooner with shorter terms and lower rates.
How do extra payments change it?+
Extra principal shortens the schedule and removes future interest, moving your payoff date earlier than the original term.
How should I use this result?+
Treat it as a planning estimate. Compare at least two realistic scenarios, then confirm with statements, quotes, or a qualified professional before acting.
How often should I refresh assumptions?+
Refresh whenever rates, income, costs, or policy limits change materially, and before making irreversible commitments.