Amortization Schedule Calculator
Build the full amortization schedule for any fixed-rate loan: monthly payment, year-by-year principal and interest breakdown, and a complete month-by-month table.
An amortization schedule is the complete month-by-month repayment table of a fixed-rate loan: each row shows the payment, the portion that went to interest, the portion that reduced principal, and the balance left afterward. Every fixed-rate loan — mortgage, auto, student, personal — follows the same rule: interest is charged on the current balance first, and only the remainder of the payment touches principal. Because the balance shrinks a little every month, the split shifts continuously: the interest share falls, the principal share grows, and the payment itself never changes. The whole table is determined by three inputs — amount, rate, and term — which is why this calculator can reproduce it exactly rather than estimate it.
This tool reports the schedule at three zoom levels: the headline figures (payment, total interest, total paid), a year-by-year rollup of principal, interest, and ending balance, and the full monthly table — with calendar dates if you set a first-payment month.
How it's calculated
The fixed payment comes from the standard annuity formula:
Payment = P · r / (1 − (1 + r)−n)
where P is the loan amount, r the monthly rate
(annual ÷ 12), and n the number of payments. The schedule
is then simulated month by month — interest = balance × r,
principal = payment − interest — with the final payment
trimmed so the balance lands exactly on zero. The yearly rollup sums
each block of 12 payments. Full formulas are on our
methodology page. For amortization as a
concept — why early payments are interest-heavy on any installment loan
— the CFPB's explainer on
amortization and auto loans
is a good primary reference.
Worked example: $300,000 at 6% over 30 years
Take the calculator's default scenario: $300,000 at 6.0% for 30 years. The payment is $1,798.65, and the loan costs $347,514.57 in total interest — more than the amount borrowed. Here is the year-by-year shape of the schedule, computed with the same engine as the tool above:
| Loan year | Principal paid | Interest paid | End balance | Cumulative interest |
|---|---|---|---|---|
| 1 | $3,684 | $17,900 | $296,316 | $17,900 |
| 5 | $4,681 | $16,903 | $279,163 | $87,082 |
| 10 | $6,313 | $15,270 | $251,057 | $166,895 |
| 15 | $8,516 | $13,068 | $213,147 | $236,904 |
| 20 | $11,486 | $10,097 | $162,011 | $293,687 |
| 25 | $15,494 | $6,090 | $93,036 | $332,632 |
| 30 | $20,898 | $685 | $0 | $347,515 |
Every row is the same $21,584 of payments; only the split moves. In year one, about 83% of the money is interest — $17,899.78 against $3,684.04 of principal — and the crossover month, the first time a payment's principal portion exceeds its interest portion, does not arrive until month 223, more than 18 years in. Halfway through the term the borrower still owes $213,147 — 71% of the original loan — because the early years retire so little principal. This is also why prepayments are most powerful early: an extra dollar in year one removes a dollar that would have been charged 6% for decades. Enter your own loan above to see where your schedule bends.
When should you use this calculator?
Use it whenever you need the balance path, not just the payment: what you will still owe at a future date (the number a sale or refinance negotiation turns on), how much interest a given loan really costs over its life, or how two term choices compare — the same amount at 15 versus 30 years produces very different tables, not just different payments. It is also the reference schedule behind the other tools here: the extra-payment calculator shows how prepayments bend this exact table, and the PMI removal calculator reads the 80% and 78% thresholds off it. Reading your own lender's schedule against this one is a quick arithmetic check on both.
The tool assumes the payment plan is followed exactly. What it cannot tell you is whether to prepay, refinance, or choose a different term — it supplies the schedule those decisions are made against.
Assumptions and limitations
- Fixed-rate, fully amortizing loans only. Adjustable rates, interest-only periods, and balloon structures are not modeled.
- Figures are principal and interest only. Escrow items — property taxes, homeowners insurance, PMI — ride on top of the payment shown.
- Interest compounds monthly (annual rate ÷ 12). Most U.S. auto loans accrue daily simple interest; results are very close but can differ by a few dollars from a lender's statement.
- The year-by-year table groups by loan year — blocks of 12 payments from the first payment — not calendar year, so year-1 interest will not match a Form 1098 unless the loan started in January. The optional first-payment month adds calendar dates to the monthly table.
- No extra payments are modeled here; that is deliberately the extra-payment tool's job.
- The final payment is trimmed to land the balance exactly on zero, so the last row is usually slightly smaller than the scheduled payment.
This page is educational content about how loan amortization works. It is not financial advice and does not consider your personal circumstances. For decisions that matter, consult a qualified professional.
Last reviewed: 2026-07-09