Mortgage Amortization Schedule Calculator
Mortgage amortization schedule calculator. Year-by-year breakdown of every monthly payment into principal + interest, cumulative interest paid, and ending balance. The honest view of total mortgage cost.
Mortgage Amortization Schedule Calculator
Year-by-year amortization schedule
| Year | Principal paid | Interest paid | Cumulative interest | Ending balance |
|---|
How to use the amortization calculator
Enter loan amount
The amount borrowed: the price minus the down payment, so USD 320,000 on a USD 400,000 home with USD 80,000 down. To look at an existing loan, enter its current balance and the years left.
Enter interest rate (%)
The fixed annual rate on the loan. The schedule divides it by 12 for each month, as a standard fixed-rate mortgage does. Use the rate from your own Loan Estimate or note.
Choose term (years)
A longer term lowers the payment and raises the total interest. At 7%, USD 320,000 costs USD 2,128.97 a month and USD 446,428 of interest over 30 years, or USD 2,876.25 a month and USD 197,725 over 15.
Read monthly P&I + total interest
The payment is principal and interest only; property tax, insurance and any mortgage insurance come on top. Total interest is every payment added up, minus the amount borrowed.
Study the year-by-year breakdown
Each row shows a year of interest and principal and the balance at its end. The crossover is the first month in which principal exceeds interest: month 242, in year 21, for a 30-year loan at 7%.
Amortization — the schedule that shows you exactly where your money goes
Amortisation is repaying a loan in equal payments over a fixed term. Each month the interest due is the balance times the monthly rate, and the rest of the payment reduces the balance. Because the balance is largest at the start, the early payments are mostly interest, and the share going to principal grows every month until the last payment clears the loan. The tool computes every month and adds them into the yearly rows.
How front-loaded the interest is
Take USD 320,000 at 7% over 30 years: a payment of USD 2,128.97. In the first month USD 1,866.67 of it, 87.7%, is interest. Even in year 10 the split is USD 19,455 of interest against USD 6,092 of principal. Principal first exceeds interest in month 242, in year 21, and half the original balance has been repaid by year 22. After five years, 60 payments totalling about USD 127,700 have reduced the balance by only USD 18,779, to USD 301,221.
Every payment is the same size. What changes is who it pays: at first almost all of it goes to the lender, at the end almost all of it goes to you.
Term, extra payments and what they save
Over 15 years the same loan costs USD 2,876.25 a month, 35% more, and USD 197,725 of interest instead of USD 446,428, 56% less. Smaller changes work the same way. An extra USD 1,000 of principal at the end of year one saves about USD 6,500 of interest over the life of the loan, because that USD 1,000 would otherwise have accrued interest for 29 years. Paying one extra monthly payment a year, which is what half-payments every two weeks amount to, repays this loan in 24 years instead of 30 and saves about USD 105,000 of interest.
Where the schedule can differ from your lender's
The arithmetic is exact for a fixed rate with monthly compounding. Lenders' statements can differ slightly because of rounding to the cent each month, the exact day interest starts, and day-count conventions. An adjustable-rate loan follows this schedule only until its first reset. In the US, IRS Publication 936 (2025) limits the mortgage interest deduction to interest on up to USD 750,000 of home acquisition debt taken out after 15 December 2017 (USD 375,000 if married filing separately), and it helps only if you itemise.
Where the payments go on USD 320,000 at 7%: 87.7% interest at first, crossover in year 21
Interest each month = balance × annual rate ÷ 12; the rest of the payment reduces the balance.
On USD 320,000 at 7% over 30 years, the first payment is 87.7% interest: USD 1,866.67 of USD 2,128.97.
In year 10 that loan still pays USD 19,455 of interest against USD 6,092 of principal.
Principal first exceeds interest in month 242 (year 21); half the balance is repaid by year 22.
After five years, 60 payments have cut the balance by only USD 18,779, to USD 301,221.
Total interest: USD 446,428 over 30 years, USD 197,725 over 15, at a 35% higher payment.
An extra USD 1,000 at the end of year one saves about USD 6,500 of interest at 7%.
One extra payment a year repays the 30-year loan in 24 years and saves about USD 105,000.
Recasting re-spreads a lump-sum reduction over the remaining term at the same rate, lowering the payment.
IRS Publication 936 (2025): interest on up to USD 750,000 of acquisition debt after 15 Dec 2017 is deductible if you itemise.
Frequently asked questions
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Because interest accrues on the outstanding balance. In month 1, your balance is the full loan amount, so the interest portion (balance × monthly rate) is large. Each subsequent month, balance shrinks slightly, so interest shrinks slightly — and more of each payment goes to principal. It's not "unfair" or a lender trick; it's the necessary consequence of compounding interest on the unpaid balance. Some borrowers don't realise it until they're 5 years in and barely above 90% LTV. The amortization table makes it visible.
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Each extra dollar of principal stops accruing interest at the loan rate for the rest of the term, so it earns that rate, risk-free. At 7%, USD 1,000 extra at the end of year one saves about USD 6,500 over the life of the loan. Whether that beats investing the money depends on what you could earn elsewhere after tax, and on keeping enough cash for emergencies, since prepaid principal is hard to get back.
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The basic mortgage calculator just gives you the monthly P&I. This tool shows the full lifecycle: year-by-year principal vs interest split, cumulative interest paid, and ending balance every year. The amortization view is what reveals the front-loaded interest, the principal-dominant crossover, and the "5 years in, only 8% paid off" reality. Both tools are useful for different stages: monthly P&I for affordability shopping, amortization schedule for understanding what you're really signing up for.
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Not directly — this calculator assumes a constant interest rate. ARMs have an initial fixed period (5, 7, or 10 years typical) then reset annually based on an index + margin. For ARM analysis, you can model the fixed period accurately and then run a separate amortization for each adjustment period using projected reset rates. Most US ARMs are now SOFR-indexed (replaced LIBOR in 2023). Pre-2010 ARMs were typically LIBOR-indexed; post-2010 SOFR. The amortization math is identical; only the rate input changes period-by-period.
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Recasting (or "re-amortization") is when you make a lump-sum principal payment and the lender re-amortizes the remaining balance over the original remaining term, producing a lower monthly payment. Differs from refinancing: same interest rate, same term-end, just spreads the smaller balance over the remaining months. Typically costs $200-$500 for the lender to recast. Useful if you receive a windfall (inheritance, bonus, stock sale) and want lower monthly payments without going through full refinance underwriting. Most conventional loans allow one recast per year; some only after specific minimum lump sums ($5K-$10K). Not all lenders offer it.
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Because the early payments are mostly interest. On USD 320,000 at 7% over 30 years, the first 60 payments total about USD 127,700, of which USD 108,959 is interest and only USD 18,779 principal, so the balance is still USD 301,221.
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In the US it can be, if you itemise. IRS Publication 936 (2025) limits the deduction to interest on up to USD 750,000 of home acquisition debt taken out after 15 December 2017 (USD 375,000 if married filing separately). Because the standard deduction is large, many borrowers do not itemise and get no benefit. Other countries have their own rules, so check with your tax authority.
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The arithmetic is exact for a fixed rate compounded monthly, and the test suite checks that the balance reaches zero on the last payment. A lender's statement can differ by small amounts because of rounding each payment to the cent, the date interest starts accruing and the day-count convention. Escrow for tax and insurance is separate and can change from year to year.
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No. Loan amount, rate, term — every input stays in your browser. The full month-by-month amortization computation runs as client-side JavaScript. Open DevTools → Network when you click Build and you'll see zero outbound requests. Safe for confidential financial planning.
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FNMA Selling Guide (selling-guide.fanniemae.com) for standard US mortgage underwriting. Consumer Financial Protection Bureau (consumerfinance.gov/owning-a-home/) for unbiased mortgage education. HUD Handbook 4000.1 for FHA loan rules. For ASEAN: MAS Singapore on housing finance, BNM Malaysia on mortgage regulations. The textbook reference: Brueggeman & Fisher's "Real Estate Finance and Investments" — the standard university-level mortgage finance text.
Method & sources
How it computes
Level payment P x r(1+r)^n / ((1+r)^n - 1), r = annual rate / 12; each month interest = balance x r, principal = payment - interest; yearly rows aggregate the months. Crossover = first month principal exceeds interest. RecaProperty.amortize, tested (balance ends at zero).
What this tool implements
- Prose figures were wrong: the first payment on $320,000 at 7% is 87.7% interest (page: ~58%); year 10 is $19,455 interest vs $6,092 principal (page: roughly 50/50); five years repays $18,779, 5.9% (page: ~8%, ~$25k); an extra $1,000 in year one saves ~$6,512 (page: $1,500-2,000).
- Confirmed: crossover month 242 (year 21), total interest $446,428 over 30 years and $197,725 over 15 (+35% payment). One extra payment a year repays in 24 years and saves ~$105,000. IRS Publication 936 (2025): $750,000 acquisition-debt limit ($375,000 MFS) for debt after 15 Dec 2017.
- Removed as unsourced: the 1934 National Housing Act and 'French amortisation' history, current-rate ranges, and Singapore HDB/bank tenure and SORA claims.
Sources
- Internal Revenue Service. Publication 936 (2025), Home Mortgage Interest Deduction. https://www.irs.gov/publications/p936
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