Amortization Schedule Calculator
Every payment on a loan, split into interest and principal — and what an extra payment each month would save you in time and interest.
The address carries whatever you changed, so anyone opening it sees these numbers. Nothing is saved on our side.
Monthly payment
$2,594.39/mo
$400,000 over 30 years at 6.75%. Add an extra payment to see what it saves.
- $533,983
- $933,983
- 360
- of 360 scheduled
- 30 years
- None
- $0
- add an extra payment
The schedule
Interest is charged on what is still owed, so it falls as the balance does. Open a year to see its individual payments.
Loan year
More of your payment goes to principal than to interest from year 21 onward.
| Year | Principal | Interest | Balance |
|---|---|---|---|
| $4,263 | $26,870 | $395,737 | |
| $4,560 | $26,573 | $391,177 | |
| $4,877 | $26,255 | $386,300 | |
| $5,217 | $25,916 | $381,083 | |
| $5,580 | $25,553 | $375,503 | |
| $5,969 | $25,164 | $369,534 | |
| $6,384 | $24,748 | $363,150 | |
| $6,829 | $24,304 | $356,321 | |
| $7,304 | $23,828 | $349,017 | |
| $7,813 | $23,320 | $341,204 | |
| $8,357 | $22,776 | $332,848 | |
| $8,939 | $22,194 | $323,909 | |
| $9,561 | $21,572 | $314,348 | |
| $10,227 | $20,906 | $304,121 | |
| $10,939 | $20,194 | $293,182 | |
| $11,700 | $19,432 | $281,482 | |
| $12,515 | $18,618 | $268,967 | |
| $13,387 | $17,746 | $255,580 | |
| $14,319 | $16,814 | $241,262 | |
| $15,316 | $15,817 | $225,946 | |
| $16,382 | $14,751 | $209,564 | |
| $17,523 | $13,610 | $192,041 | |
| $18,743 | $12,390 | $173,299 | |
| $20,048 | $11,085 | $153,251 | |
| $21,444 | $9,689 | $131,808 | |
| $22,937 | $8,196 | $108,871 | |
| $24,534 | $6,599 | $84,337 | |
| $26,242 | $4,891 | $58,095 | |
| $28,069 | $3,064 | $30,026 | |
| $30,026 | $1,109 | $0 |
How this calculator works
The same three lines, repeated once per payment.
interest = balance × (rate ÷ 12)
principal = payment − interest
balance = balance − principal
The payment itself is fixed by the standard amortizing-loan formula. Because the balance falls each month, the interest portion falls with it and the principal portion grows — the whole shape of a loan comes out of those three lines.
Interest is rounded to the cent each month, the way a servicer rounds it, and the final payment absorbs the drift, which is why the last balance is exactly zero rather than a few cents either side.
Extra payments
An extra amount is added to every payment and goes entirely against the principal. That shortens the loan rather than reducing the scheduled payment, so the saving compounds: a smaller balance next month means less interest, which means more principal, and so on until the loan ends early.
A worked example
Four hundred thousand dollars at 6.75% over thirty years, with and without an extra $200.
| Loan amount | $400,000 |
|---|---|
| Monthly payment | $2,594.39 |
| First month's interest | $2,250.00 |
| First month's principal | $344.39 |
| Interest with no extra | $533,983 |
| Paying $200 extra | $2,794.39 |
| Payments actually made | 292 |
| Interest saved by the extra $200 | $119,112 |
The extra payments come to $58,400 over those 292 months and remove $119,112 of interest — more than twice the money put in. The difference is the interest those dollars would otherwise have accrued over the remaining term.
Questions people ask
Because interest is charged on what you still owe, and at the start you owe almost everything. On a 30-year loan at 6.75%, the first payment is roughly 87% interest. The proportion shifts every month, slowly at first and then quickly — which is why the crossover point where principal overtakes interest arrives about two thirds of the way through the term.
More than the extra money, because every extra dollar removes all the future interest that dollar would have accrued. On a $400,000 loan at 6.75%, an extra $200 a month saves over five years and six figures of interest. The saving comes from time, not from the payments themselves.
Monthly, marginally, because the money starts reducing the balance sooner. The difference is small — the size of the extra payment matters far more than its timing. What matters more is that the lender applies it to principal rather than holding it as a prepaid instalment; some require you to say so explicitly.
Yes. Any fixed-rate loan repaid in equal instalments amortizes the same way — car loans, personal loans, student loans, equipment finance. The term lengths differ; the mathematics does not.
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An estimate. Your servicer's schedule may differ by a few cents from rounding, and any escrow for taxes and insurance sits on top of these figures.