Free mortgage amortization calculator
Generate a full mortgage amortization schedule — see each payment broken into principal and interest, the running balance, and total interest paid, updated live, as you type.
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Estimate only. Actual payments may vary. PMI rate assumed 0.5% if down payment < 20%. Consult a licensed lender for exact terms.
Results are estimates. Consult a professional.
How the mortgage amortization calculator works
Amortization is the method lenders use to keep your monthly payment fixed while gradually shifting the split between interest and principal. In the early years nearly every dollar pays interest. By the final months nearly every dollar retires debt. The calculator generates the full month-by-month schedule from three inputs: loan amount, interest rate, and term.
Repeat those three arithmetic steps 360 times for a 30-year loan and the balance hits zero on the final payment. That is the entire amortization schedule. The calculator does this instantly and shows you any month you choose.
Amortization formula: Fannie Mae Single Family Servicing Guide, Section D2-3.2; CFPB mortgage documentation.Worked example: $350,000 at 7% over 30 years
A buyer takes out a $350,000 mortgage at 7% fixed over 30 years. The monthly P&I payment is $2,329. Let's trace what happens in month 1, month 60, and month 300.
When is 25%/50%/75%/90% of principal paid off?
Because early payments are mostly interest, equity builds slowly at first. The table below shows — for a standard 30-year loan at three common rates — the month when each principal milestone is crossed. Use it to plan refinance timing, PMI removal, or home-equity borrowing.
| Milestone | 6% — month (year) | 7% — month (year) | 8% — month (year) |
|---|---|---|---|
| 25% principal paid | Month 217 (yr 18) | Month 222 (yr 18.5) | Month 227 (yr 19) |
| 50% principal paid | Month 252 (yr 21) | Month 257 (yr 21.5) | Month 262 (yr 22) |
| 75% principal paid | Month 291 (yr 24) | Month 294 (yr 24.5) | Month 297 (yr 25) |
| 90% principal paid | Month 322 (yr 27) | Month 324 (yr 27) | Month 326 (yr 27) |
Source: standard amortization schedule math. 30-year fixed, any loan amount (milestones are percentage-based and scale identically).
Notice that higher rates push every milestone later. At 8%, you cross the 50% paid mark about 10 months later than at 6%. Over a 30-year term, that difference is meaningful when planning a cash-out refinance or a home sale.
Tips for using the amortization schedule
The amortization schedule is more than a curiosity. Each row is a decision point — for extra payments, refinancing, or PMI removal. Here is how to read it strategically.
- Find your PMI drop-off month — locate the row where your remaining balance falls to 80% of the original home value. That is when you can request PMI cancellation under the Homeowners Protection Act.
- Time extra payments early — every extra dollar paid in years 1–7 eliminates far more future interest than the same dollar paid in years 20–28. The interest column tells you the exact stakes each month.
- Use the schedule before refinancing — find the month you are currently in, note the remaining balance, and use that number (not the original loan) as the principal when modeling a refinance.
- Check equity before selling — subtract the current balance row from your home's estimated value to see your net equity before agent commissions and closing costs.
- Run 15-year and 30-year side by side — the total-interest row at the bottom of each schedule makes the lifetime cost difference undeniable. Most borrowers are surprised how large it is.
Accuracy and limitations
This calculator uses the standard fixed-rate amortization formula applied month by month to an exact balance. Results match lender-generated schedules to within rounding on each monthly payment. The schedule assumes you make every payment on time, on the same date each month, with no skipped or partial payments. Biweekly payment plans, lump-sum prepayments, or missed payments are not modeled here.
Not financial advice — consult a mortgage professional for your specific situation.
Amortization terms defined
About this mortgage amortization calculator
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