Mortgage amortisation calculator
See how each payment splits between interest and principal, and follow the balance down year by year until the mortgage is repaid.
Fixed rate, no extra payments, no fees. Amounts rounded to the nearest dollar.
Amortisation schedule (year by year)
| Year | Interest paid | Principal paid | Balance left |
|---|---|---|---|
| 1 | $14,916 | $3,070 | $246,930 |
| 2 | $14,727 | $3,259 | $243,671 |
| 3 | $14,526 | $3,460 | $240,210 |
| 4 | $14,313 | $3,674 | $236,536 |
| 5 | $14,086 | $3,900 | $232,636 |
| 6 | $13,846 | $4,141 | $228,495 |
| 7 | $13,590 | $4,396 | $224,098 |
| 8 | $13,319 | $4,668 | $219,431 |
| 9 | $13,031 | $4,955 | $214,475 |
| 10 | $12,725 | $5,261 | $209,214 |
| 11 | $12,401 | $5,586 | $203,629 |
| 12 | $12,056 | $5,930 | $197,699 |
| 13 | $11,691 | $6,296 | $191,403 |
| 14 | $11,302 | $6,684 | $184,719 |
| 15 | $10,890 | $7,096 | $177,622 |
| 16 | $10,452 | $7,534 | $170,088 |
| 17 | $9,988 | $7,999 | $162,089 |
| 18 | $9,494 | $8,492 | $153,597 |
| 19 | $8,971 | $9,016 | $144,581 |
| 20 | $8,414 | $9,572 | $135,009 |
| 21 | $7,824 | $10,162 | $124,847 |
| 22 | $7,197 | $10,789 | $114,057 |
| 23 | $6,532 | $11,455 | $102,603 |
| 24 | $5,825 | $12,161 | $90,441 |
| 25 | $5,075 | $12,911 | $77,530 |
| 26 | $4,279 | $13,708 | $63,823 |
| 27 | $3,433 | $14,553 | $49,270 |
| 28 | $2,536 | $15,451 | $33,819 |
| 29 | $1,583 | $16,404 | $17,415 |
| 30 | $571 | $17,415 | $0 |
How this calculator works
An amortisation schedule is the month-by-month ledger of a mortgage. Each payment first covers the interest accrued on the remaining balance, and whatever is left reduces the principal. Your payment is fixed, but the split is not: on a 30-year loan at 6%, the first payment is $1,250 of interest and only about $249 of principal, while the final payment is almost entirely principal.
The table below is generated from the same formula as the calculator and shows, for each year, how much interest you paid, how much principal you cleared and what is still owed. It is the schedule lenders use, assuming no extra payments, no late fees and a fixed rate. Any extra principal you pay shortens the schedule and moves every later row forward.
The formula
Payment M comes from the standard amortisation formula with r = APR ÷ 12 ÷ 100 and n = months. For month i:
interest_i = balance_(i−1) × r
principal_i = M − interest_i
balance_i = balance_(i−1) − principal_iThe final payment is adjusted down so the balance lands exactly on zero. Total interest is M × n − P.
Worked example
On a 250,000 mortgage at 6% over 30 years the payment is $1,498.88. The first payment contains $1,250.00 of interest and only $248.88 of principal. Across the whole term you pay $289,595.47 in interest. The table below shows the same numbers totalled by year.
Common mistakes
- Reading the first month as typical. The early schedule is mostly interest. Halfway through a 30-year loan the balance is still around 75% of the original amount.
- Ignoring the effect of extra payments. An extra $100 a month this early is not just $100 off the total — it removes all future interest on that amount, which is why small prepayments shorten a 30-year loan by years.
- Assuming the schedule covers taxes. Escrowed property tax and insurance do not amortise at all. Only the principal-and-interest part follows this schedule.
Frequently asked questions
What does amortisation mean?
Amortisation is the process of paying a loan down through regular payments that cover both interest and principal. A fully amortising loan ends with a zero balance exactly at the end of its term.
Why is most of my early payment interest?
Interest is charged on the entire outstanding balance. At the start the balance is at its largest, so the interest charge is largest; as the balance falls, more of each payment can go to principal.
How much faster does the loan pay off with extra payments?
It depends on when the extra payments start and how large they are. Paying even a small extra amount in the first years has a disproportionate effect because it removes interest from every following month. Recalculate with a lower loan amount to approximate the effect of a lump-sum prepayment.
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