Mortgage Amortization Calculator
A full year-by-year and month-by-month mortgage amortization breakdown with extra payments.
About Mortgage Amortization Calculator
An amortization schedule shows how each payment splits between principal and interest. In the early years of a mortgage, the vast majority of each payment is interest — on a 30-year loan at 6.5%, more than 70% of the first payment is interest. As the principal balance falls over time, the interest portion shrinks and the principal portion grows. By the final payment, almost the entire amount is principal.
Formulas
Monthly payment
M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1)
- P
- Principal
- r
- Monthly rate (annual ÷ 12)
- n
- Number of months
- M
- Monthly payment
Per-period interest
Interest in period k = Balance at start of period × Monthly rate
- B_{k-1}
- Balance at start of period
- r
- Monthly rate
Per-period principal
Principal in period k = Payment − Interest in period k
Worked example
With the default values below, Mortgage Amortization Calculator returns Monthly Payment (P&I) of $2,212.24. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Loan Amountaccepts 1,000–10,000,000 $
- 350,000 $
- Annual Interest Rateaccepts 0–20 %
- 6.5 %
- Loan Termaccepts 1–40 years
- 30 years
- Extra Monthly Paymentaccepts 0–50,000 $
- 0 $
- First Payment Date
Results
- Monthly Payment (P&I)
- $2,212.24
- Total Interest Paid
- $446,406
- Total Amount Paid
- $796,406
- Loan Amount
- $350,000
- Payoff in
- 360 months
- Time Saved by Extra Payments
- 0 months
Step by step
- 1Scheduled monthly payment (P&I)= $2,212.24
- 2Payoff timeline= 30 years 0 months (360 payments)
- 3Total interest cost= $446,406
- 4Total amount paid= $796,406
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or fees or charges into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- Schedule assumes a fixed interest rate throughout the loan term. Actual statements may vary due to payment timing, rounding and escrow adjustments.
- This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Schedule assumes a fixed interest rate throughout the loan term. Actual statements may vary due to payment timing, rounding and escrow adjustments.
Frequently Asked Questions
Why does so little of my early payment go to principal?
Because interest is charged on the full outstanding balance. At the start of a $350,000 loan at 6.5%, you owe $1,895.83 in interest in month 1 alone. Only the amount above that reduces the principal. As you pay down the balance, the monthly interest charge falls and more of each payment goes to principal.
What happens to the schedule when I make an extra payment?
Every extra dollar goes directly to principal, reducing the balance on which next month's interest is computed. This creates a compounding benefit: not only does the balance drop faster, but every subsequent payment contains slightly less interest and more principal. Even a single extra payment early in the loan has a ripple effect.
How do I read the cumulative interest column?
The cumulative interest column shows the total interest paid from the start of the loan through each month. This is useful for tax planning (if your mortgage interest is deductible) and for visualising the total cost of the loan at any point in time.
When does my equity reach 20% (80% LTV)?
Look at the balance column in the monthly schedule and find the row where the balance falls to 80% of your original purchase price. That is the month you can request PMI cancellation if you have a conventional loan.