Amortization Schedule Calculator
Generate a full amortization schedule for any loan. See the breakdown of principal and interest for every payment.
A $200,000 loan at 6% over 30 years costs $1,199 a month and $231,676 in total interest — more than the amount borrowed, with only 17% of the first payment reducing the balance.
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What Is an Amortization Schedule?
An amortization schedule shows every payment broken down into principal and interest. Early payments are mostly interest; later payments are mostly principal.
Worked example
Using the defaults — a $200,000 loan at 6% over 30 years:
Monthly rate r = 6% ÷ 12 = 0.005, n = 360 payments.
Compute the payment. (1.005)^360 = 6.0226. The payment is $200,000 × 0.005 × 6.0226 ÷ 5.0226 = $1,199 per month.
Split the first payment. Interest in month one is $200,000 × 0.005 = $1,000. Principal is $1,199 − $1,000 = $199. Only 17% of your first payment touches the balance.
Watch the crossover. The balance falls $199 in month one, so month two interest is $199 lower × 0.005 = about $1.00 less. The principal share grows slowly at first and rapidly later. The payment splits evenly around month 222 — about year 18.5.
Total the cost. $1,199 × 360 = $431,640. Total interest is $431,640 − $200,000 = $231,640 — you pay more in interest than you borrowed, and more than half of it accrues in the first decade.
Enter 200000, 6 and 30 above to reproduce the $1,199 payment. The full month-by-month breakdown is in the schedule table below the results.
The same $200,000 loan across terms and rates
Term length changes the monthly payment far less than it changes the total interest bill.
| Term | Rate | Monthly payment | Total interest | Interest as % of principal |
|---|---|---|---|---|
| 15 years | 5.75% | $1,661 | $98,948 | 49% |
| 20 years | 6.00% | $1,433 | $143,887 | 72% |
| 30 years (default) | 6.00% | $1,199 | $231,676 | 116% |
| 30 years | 7.00% | $1,331 | $279,018 | 140% |
| 30 years | 5.00% | $1,074 | $186,512 | 93% |
Going from 30 years to 15 years raises the monthly payment by $462 but removes $132,728 of interest. The monthly difference is the entire trade-off.
Common mistakes with this calculation
- Judging affordability from the monthly payment alone. A 30-year loan at $1,199 a month looks easier than a 15-year loan at $1,660. It costs $132,840 more in interest. The monthly payment is the visible number; the total cost is the real one.
- Assuming extra payments shorten the term proportionally. Extra principal attacks the balance directly, so every dollar saved there also removes all the future interest that dollar would have accrued. A $100 monthly extra on this loan can cut roughly five years — more than a naive linear estimate suggests.
- Refinancing for a lower payment rather than a lower cost. Restarting the clock at 30 years lowers the payment and often raises the total interest, because you have re-borrowed the part you had already repaid. Always compare total cost, not monthly outlay.
- Ignoring escrow in the payment figure. Property tax and insurance are usually collected monthly into escrow. They are not part of the amortisation and do not reduce the balance, but they appear in the same payment. Separate them before comparing offers.
When this calculator does not apply
- The calculator assumes a fixed rate for the entire term. Adjustable-rate loans reset and require a rate-path assumption.
- It assumes no extra payments, no late payments, and no fees rolled into the principal.
- Escrow components — property tax, insurance, PMI — are excluded, so the real monthly outlay is higher than the amortised payment.
- It does not model the tax deductibility of mortgage interest, which changes the effective cost for many borrowers.
- Rounding means the final payment may differ slightly from the rest of the schedule.
Frequently Asked Questions
Why does interest decrease over time?
Each payment reduces your principal balance. Since interest is calculated on the remaining balance, less principal means less interest each month.
Can I see the full schedule?
Yes, the calculator shows the first 12 months and the last 6 months. The full schedule is available in the calculation output.
Sources & Methodology
This calculator uses standard financial formulas. See our methodology page for the full formula derivation.
- Mortgage Calculator and Amortisation Consumer Financial Protection Bureau
- What Is a Mortgage? Consumer Financial Protection Bureau
- Consumer Handbook on Adjustable-Rate Mortgages Consumer Financial Protection Bureau
- Mortgage Interest Deduction Internal Revenue Service
- Housing Finance Data Federal Reserve
Last reviewed .
Key takeaways
- $200,000 at 6% over 30 years is a $1,199 payment and $231,640 of interest — more than the principal.
- Only 17% of the first payment reduces the balance. The split reaches even around year 18.5.
- A 15-year term costs $132,840 less in interest and $461 more per month.
- Extra principal payments remove both the balance and all future interest on it.
- Refinancing to lower the payment can raise the total cost. Compare totals, not instalments.