Amortization Schedule Calculator
View detailed loan repayment schedule
Input Information
Result
Enter values and press Calculate.
Amortization Schedule Calculator takes the loan amount, annual rate, term, and repayment method and shows month by month how much of each payment is principal, how much is interest, and what balance remains after every single payment.
Unlike calculators that only quote a monthly figure, an amortization schedule reveals where your money actually goes. Early payments are heavily weighted toward interest, and only in later years does principal reduction accelerate — seeing that structure makes decisions like when to prepay or which repayment method to choose far clearer.
Equal Installment (PMT) pays one fixed amount every month; Equal Principal repays a constant slice of principal plus interest on the shrinking remainder. Comparing both side by side exposes the trade-off between total interest and initial burden.
- 1
Enter the loan terms
Fill in the amount, annual rate (%), and term in years. Defaults are 100 million at 5% for 10 years.
- 2
Choose the repayment method
Pick Equal Installment or Equal Principal — switching back and forth shows exactly how the two methods differ.
- 3
Calculate and read the summary
The summary card shows first-month payment, total interest, total paid, and the interest share.
- 4
Read the monthly table
In the monthly schedule below, trace the Payment / Principal / Interest / Balance columns. Interest shrinking while principal grows month over month is the whole story.
Example — 100 million at 5% for 10 years
Using the default conditions (100 million, 5% annually, 120 payments), the monthly rate is 5% ÷ 12 ≈ 0.4167%. Under Equal Installment:
- Monthly payment: about 1,060,655, identical for all 120 months
- Month 1 split: 416,667 interest + 643,988 principal
- Total paid ≈ 127.29 million → total interest ≈ 27.29 million (about 21.4%)
Switching the same loan to Equal Principal fixes the principal slice at 833,333 per month. Month one costs 1,250,000 (833,333 + 416,667 interest), but by the final month interest has fallen to about 3,472, so the payment drops to roughly 836,806. Total interest comes to exactly 25,208,333 — about 2 million less than PMT — provided the heavier early payments fit your budget.
Equal Installment (PMT Formula)
- M = Monthly payment
- P = Loan principal
- r = Monthly interest rate (annual/12)
- n = Total number of payments (term × 12)
Equal Principal
Interest = Balance × Monthly rate. Principal is equal each month while interest decreases.
In both methods interest accrues first on the prior balance; under PMT the rest of the fixed payment goes to principal, under Equal Principal the principal slice is deducted first and interest added on top. That ordering difference alone compounds into millions over a decade.
PMT vs Equal Principal
PMT keeps early payments manageable; Equal Principal minimizes total interest. On identical terms the gap can exceed two million won.
Prepayment Fees
Schedules are estimates; early repayment may trigger penalties — typically 1–1.5% of remaining principal within the first three years. Confirm with your lender.
Rate Changes
Variable-rate loans redraw the entire schedule whenever the benchmark moves. Simulate a +1 percentage-point shock here before it happens.
QWhich is better — equal installment or equal principal?
Equal principal always wins on total interest. In the worked example below, borrowing 100 million at 5% for 10 years costs about 27.3 million in interest with equal installments versus about 25.2 million with equal principal — roughly 2 million saved. The catch is that early equal-principal payments are much heavier (~1.25 million vs ~1.06 million). Choose equal installment for payment stability, equal principal if cash flow allows the heavier start.
QIf my payment is fixed, why do interest and principal portions change each month?
Interest is always computed on the remaining balance: balance × monthly rate. In month one the full principal is outstanding so interest is highest; as the balance shrinks, the interest portion shrinks too. Since your payment stays constant, whatever interest no longer consumes flows straight to principal — later payments attack the debt faster.
QWhen is the best time to prepay?
The earlier the better. Because equal-installment schedules front-load interest, the same prepayment amount early in the loan eliminates far more future interest than late. On the terms above you will already have paid close to 60% of all interest by year five. Still, check any prepayment penalty window (often three years) and keep an emergency fund first.
QWhy does my bank's statement differ from this schedule?
This calculator models a pure scenario: fixed rate, no prepayments, no fees. Real loans shift with rate resets, extra payments, penalty charges, and collateral costs. Variable-rate loans in particular get their payments recalculated when rates move — treat this schedule as the baseline of what happens if today's rate held to maturity.
QWhat does the interest ratio mean?
It is the share of everything you pay that goes to interest. In the example above, about 21.4% of the 127.3 million total is interest. The same rate stretched over a longer term pushes this ratio up dramatically — on a 30-year loan nearly half of all money paid can be interest — which is why this metric deserves a look before extending a term.