Amortization calculator with extra payments
See your full payment schedule, how each payment splits between interest and principal, and how extra payments change it. Switch the table between annual and payment-by-payment views.
Your schedule, with and without extra payments
Change any field and the schedule updates instantly. Nothing you type leaves your browser.
An amortization schedule splits every payment into interest and principal. On a $300,000, 30-year loan at 6.5%, the first payment of $1,896.20 is $1,625.00 interest and only $271.20 principal. Adding $200 a month cuts the schedule from 360 payments to 277 and saves about $103,449 in interest.
How to read the schedule above
- Annual view: one row per year, comparing the scheduled loan with the accelerated one (balance and interest) and the extra amount applied that year.
- Monthly view: one row per payment of the accelerated schedule: payment number, date, total payment, interest, principal, extra principal and the balance left.
- Export CSV: downloads whichever view is selected, so you can open it in a spreadsheet.
To see the loan without extra payments, set the extra amount to zero. The calculator covers principal and interest only; property taxes, insurance and mortgage insurance are not included.
How the split between interest and principal changes
The payment stays the same ($1,896.20 a month), but its makeup does not. Each month, interest is the balance times the monthly rate, and whatever is left of the payment reduces the principal. Here is what that looks like across a 30-year loan, with no extra payments:
| Year of the loan | Interest paid that year | Principal paid that year | Share going to principal |
|---|---|---|---|
| Year 1 | $19,401 | $3,353 | 14.7% |
| Year 5 | $18,409 | $4,346 | 19.1% |
| Year 10 | $16,745 | $6,009 | 26.4% |
| Year 15 | $14,445 | $8,310 | 36.5% |
| Year 20 | $11,263 | $11,491 | 50.5% |
| Year 25 | $6,864 | $15,890 | 69.8% |
| Year 30 | $781 | $21,973 | 96.6% |
Assumptions: new $300,000 loan, 30-year fixed rate of 6.5%, no extra payments. Method: How the calculator works.
On this loan, a monthly payment includes more principal than interest for the first time in payment 233, which is 19 years and 5 months in. That is why the early years matter so much: for a long time, most of what you pay is the cost of borrowing.
What an extra payment does to the schedule
An extra payment goes entirely to principal. That lowers the balance, so the interest charged the next month is smaller, and more of the regular payment then goes to principal as well. The effect compounds. Compare the balance left on the same loan with and without an extra $200 a month:
| Time elapsed | Balance, no extra | Balance, +$200 a month | Difference |
|---|---|---|---|
| 5 years | $280,833 | $266,698 | $14,135 |
| 10 years | $254,328 | $220,648 | $33,681 |
| 15 years | $217,677 | $156,968 | $60,709 |
| 20 years | $166,996 | $68,912 | $98,084 |
| 25 years | $96,912 | $0 | $96,912 |
Same assumptions, with $200 added to principal every month from the first payment. The loan with extra payments ends in month 277 (23 years and 1 month); the final payment is $632.35.
Two milestones show the shift. With the extra $200, principal (including the extra) outweighs interest from payment 149 (12 years and 5 months) instead of payment 233. And half of the original $300,000 is repaid after 15 years and 6 months instead of 21 years and 5 months. For the full set of savings by amount, see What happens if you pay an extra $200 a month.
The math behind the schedule
The scheduled payment comes from the standard loan formula: payment = balance × r ÷ (1 − (1 + r)−n), where r is the monthly rate (the annual rate divided by 12) and n is the number of monthly payments. Each month, interest = remaining balance × r, and principal = payment − interest. Your lender’s own schedule may differ by a few cents or dollars because of rounding, how the first payment date is set, and whether interest is calculated daily. The details are in How the calculator works.
Check these things before you pay extra
- Prepayment penalty. The CFPB says penalties do not normally apply if you pay extra principal in small chunks, but recommends confirming with your lender. See Prepayment penalty: what it is and how to check yours.
- Make sure it goes to principal. Ask your servicer how to designate an extra payment as principal-only, and confirm on your next statement that the balance dropped by the extra amount.
- Compare with your lender’s schedule. Use the balance on your statement as the starting point, and the remaining term, not the original one.
If you want a calculator focused on the savings, try the extra mortgage payment calculator or the car loan extra payment calculator.
Frequently asked questions
What is an amortization schedule?
How do extra payments change an amortization schedule?
Why is most of my early payment interest?
Can I download the schedule?
Does the schedule include taxes and insurance?
Sources and method
- All figures were calculated with the Financial Accelerator engine; the formulas and assumptions are public in How the calculator works.
- Consumer Financial Protection Bureau, What is a prepayment penalty? (reviewed September 11, 2024).
This page is educational and not financial, legal or tax advice. Estimates assume a fixed rate and that extra money is applied to principal. Confirm the terms of your own loan with your lender.