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Loan Amortization Calculator

Generate the full payment-by-payment schedule with real calendar dates — every installment's principal/interest split, the running balance, and the exact payoff month.

By Avinash Verma · editorial standards Last reviewed: Formula v1.0 · How we calculate

Inputs

How to use this calculator

Alongside the usual amount, rate and term, this calculator asks when the first payment falls due (month and year), so every row in the schedule carries a real calendar date instead of "payment 137". That makes the output directly comparable with lender statements and useful for planning around specific dates.

  • Loan amount, rate, term come from your agreement or the offer you are evaluating.
  • First payment month and year is typically one month after closing or disbursal.
  • Switch the table between Annual (one row per loan year, with the year-end date) and Monthly (every installment).
  • Export to CSV to reconcile against your servicer's statement or to build projections in a spreadsheet.

How to read an amortization schedule

An amortization schedule writes out the loan's entire future, one row per payment: the date, the payment made, how much of it repaid principal, how much was consumed by interest, and the balance still owed afterwards. Two identities hold on every correct schedule: principal + interest = payment (for loans without escrow), and each row's balance = previous balance − that row's principal. If a schedule you've been given breaks either rule, some other charge is flowing through the payment.

Follow the default loan here: $200,000 at 6% over 20 years, first payment July 2026. The payment is $1,432.86 every month, but the first row splits it as $1,000.00 interest / $432.86 principal: at the start, 70% of the payment is rent on the money. Scan down the schedule and the split migrates one notch each month. The crossover, the first row where principal exceeds interest, arrives at payment #103, January 2035, more than eight years in. Only from that point does the majority of each payment build equity rather than pay for time.

The balance column tells the same story from a different angle. At the schedule's halfway point, June 2036, the balance is still $129,062.84: after 120 of 240 payments, only 35.5% of the principal is gone. The balance curve is bowed, not straight: it sheds its last $100,000 in far less time than its first. This bow is why "I've paid for ten years, I must own half" is one of the most common misreadings in consumer finance, and why the schedule, not intuition, should drive decisions about selling, refinancing or prepaying.

Practical uses for the dated rows: find the balance on the date you plan to sell or refinance (that is your payoff figure, before per-diem interest); check when the balance crosses a threshold that releases you from collateral requirements; or confirm the final payment date (June 2046 here) against your servicer's records. The CSV export mirrors the table exactly, so a spreadsheet VLOOKUP against your statement can flag any month where the servicer's applied principal drifts from the schedule.

Formula and methodology

The schedule is generated by iterating one rule from the first payment date:

Ik = Bk−1 × r  ·  Pk = M − Ik  ·  Bk = Bk−1 − Pk
  • Bk balance after payment k (B0 = loan amount)
  • Ik, Pk interest and principal portions of payment k
  • M the level payment from the standard amortization formula
  • r monthly rate = annual rate ÷ 12

Dates advance one calendar month per row from the start month you choose. The crossover row is the first k where Pk > Ik, which happens when the balance falls below M ÷ (2r); the calculator finds it by inspection of the rows. The final payment is trimmed by a few cents where necessary so the balance lands on exactly zero.

Worked example

Example: $200,000 at 6% for 20 years, first payment July 2026

Monthly rate r = 0.06 ÷ 12 = 0.005; (1.005)240 = 3.31020, giving M = 200,000 × 0.005 × 3.31020 ÷ 2.31020 = $1,432.86.

Row 1 (Jul 2026): interest $1,000.00, principal $432.86, balance $199,567.14. First year's interest: $11,854.75.

Crossover at row 103 (Jan 2035): principal $719.93 finally edges past interest $712.94.

Row 120 (Jun 2036, halfway): balance $129,062.84 — 35.5% of the principal repaid at 50% of the term.

Row 240 (Jun 2046): balance $0. Lifetime interest $143,886.91 on $343,886.91 total paid.

What changes the result

  • Rate sets the crossover. Higher rates push the principal/interest crossover later. At low rates principal dominates from the first payment; the 6% default crosses in year 9.
  • Term stretches the bow. Longer schedules deepen the curve in the balance chart, concentrating equity growth into the final third of the loan.
  • Start date shifts every row. Moving the first payment from July to a January makes year boundaries align with tax years, which is handy where loan interest is deductible.
  • Payment posting discipline. A servicer applying your payment days late alters each row's interest slightly; reconciling the CSV against statements catches this drift early.

Assumptions and limitations

  • The schedule assumes every payment posts on time and in full; missed or late payments re-shape all subsequent rows.
  • Fixed rate only; a rate reset invalidates the schedule from the reset date forward.
  • Rows show principal and interest only. Escrow, insurance and fees that servicers often blend into the payment line are excluded.
  • Payoff quotes from lenders add per-diem interest between your statement date and the payoff date, so they run slightly above the scheduled balance.
  • Extra payments are not modeled here; pair this schedule with the extra payment calculator to see a modified one.

Frequently asked questions

What exactly do the columns in the schedule mean?

Date is when the payment falls due. Payment is the cash out the door that month. Interest is the previous balance × the monthly rate, the cost of having the money. Principal is payment minus interest, the part that actually reduces the debt. Balance is what remains owed after the payment posts. Only the principal column builds equity; the interest column is pure cost.

Why is my balance so high after years of payments?

Because early payments are mostly interest. On the default schedule, 120 on-time payments (ten full years) still leave $129,062.84 of the original $200,000 owed. The balance falls on a bowed curve that steepens over time, so equity accumulates slowly at first and rapidly at the end. The remaining-balance chart above shows the exact shape for your inputs.

What is the principal/interest crossover and does it matter?

It is the first payment where more than half goes to principal — payment #103 (January 2035) on the default loan. It has no contractual significance, but it is a useful milestone: before it, prepayments and refinancing decisions have their largest effect; after it, the majority of the lifetime interest is already paid and those levers weaken. Knowing your crossover date tells you which side of that divide you are on.

How do I reconcile this schedule with my lender's statement?

Export the CSV and place your statement's figures beside the matching dated row. The interest column should agree to within pennies if your lender accrues monthly; persistent small gaps suggest daily accrual, and a one-off jump usually means a payment posted off its due date. If the principal applied is consistently lower than scheduled, check whether fees or escrow shortages are being deducted from your payment before principal.

Can I use this for a mortgage, car loan or student loan?

Any fixed-rate, monthly-payment loan amortizes this way, so yes for standard mortgages (principal and interest portion only), car loans and most refinanced student loans. It does not fit credit cards or lines of credit, which have no fixed schedule, or interest-only and balloon structures where the level-payment formula doesn't apply.