Free Amortization Calculator

Amortization Schedule Calculator

Generate a complete amortization schedule for any loan. See every payment broken down into principal and interest, view yearly summaries, model extra payments, and export to CSV.

P&I
Full breakdown
Every payment, every month
CSV
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Open in Excel or Sheets

Amortization Schedule Calculator

Loan Details

Loan Amount
$
Annual Interest Rate
%
Loan Term
Start Date

Extra payments (optional)

Extra Monthly Paymentaccelerate payoff
$

Enter loan details and click Generate Schedule

What Is an Amortization Schedule?

An amortization schedule is a complete payment-by-payment breakdown of a loan, showing exactly how each payment is split between principal (reducing the loan balance) and interest (the cost of borrowing). It also shows the remaining balance after each payment.

Every fixed-rate installment loan — mortgage, auto, personal, student — follows the same amortization math: equal monthly payments, but the principal/interest split shifts over time.

How Amortization Works: The Front-Loading Effect

Interest is calculated as a percentage of your outstanding balance each month. Since your balance is highest at the beginning, early payments are mostly interest. As the balance shrinks, less interest accrues — so more of each payment goes to principal.

Example: $300,000 mortgage at 6.11% — 30 years
Month 1$902 principal$1,528 interest$299,098 balance
Month 12$958 principal$1,472 interest$289,742 balance
Month 60$1,165 principal$1,265 interest$248,264 balance
Month 180$1,703 principal$727 interest$141,826 balance
Month 300$2,305 principal$125 interest$24,175 balance
Month 360$2,428 principal$12 interest$0 balance

How Extra Payments Save You Money

Extra principal payments permanently reduce your balance — which reduces future interest charges. The earlier you make extra payments, the more you save, because you avoid interest on the removed balance for the remaining life of the loan.

Here's what different extra payment amounts save on a $300,000 loan at 6.11%:

Extra/MoTotal InterestPayoffInterest Saved
$0$348,09030 yr—
$100$317,23027 yr 5 mo$30,860
$200$289,91025 yr 1 mo$58,180
$300$265,40023 yr 2 mo$82,690
$500$223,07020 yr 1 mo$125,020
$1,000$162,47015 yr 9 mo$185,620

Based on $300,000 loan at 6.11% APR, 30-year term.

Amortization Formula

The monthly payment is calculated using the standard PMT formula used by every U.S. bank and lender:

M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]
M = Monthly paymentP = Principal (loan amount)r = Monthly rate (annual rate ÷ 12)n = Total payments (years × 12)

Each month's interest is calculated as: Interest = Balance × (Annual Rate ÷ 12). Principal paid = Monthly Payment − Interest. The balance decreases by the principal portion each month.

Tips for Using Your Amortization Schedule

  • Identify your break-even on refinancing. Find the month where your remaining interest savings exceed closing costs.
  • Model lump-sum payments. Use the extra payment field to see how a one-time principal payment affects your payoff date.
  • Plan your payoff target. Want to pay off in 20 years instead of 30? Calculate the extra payment needed.
  • Tax planning. In the U.S., mortgage interest is deductible for itemizers. Your amortization schedule shows exactly how much interest you paid in any tax year.
  • Verify lender statements. Your lender's monthly statement should match this schedule exactly (for fixed-rate loans).
FAQ

Amortization Schedule — Common Questions

What is an amortization schedule?
An amortization schedule is a complete table of every loan payment — showing how each payment is divided between principal (reducing your balance) and interest (the cost of borrowing). It also shows your remaining balance after each payment. This tool generates the full schedule for any loan, with the option to see monthly detail or a yearly summary.
Why do early mortgage payments go mostly to interest?
Interest is calculated on your outstanding balance each month. Early in the loan, your balance is at its highest — so interest charges are at their maximum. As you pay down principal over time, each month's interest charge decreases, and more of your fixed payment goes to principal. On a $300K, 30-year loan at 6.11%, your first payment is about $730 interest and $902 principal. By year 25, it flips to ~$200 interest and $1,430 principal.
How do extra payments affect the amortization schedule?
Extra payments go entirely to principal — reducing the balance faster. This means future interest is calculated on a lower balance, and the loan pays off sooner. On a $300K mortgage at 6.11%: an extra $100/mo saves ~$31K in interest and 2.5 years. An extra $300/mo saves ~$79K and 7+ years. The savings are front-loaded — extra payments in early years save the most.
What is the difference between principal and interest?
Principal is the original amount you borrowed — each principal payment permanently reduces your loan balance. Interest is the lender's fee for lending you money — it's calculated as a percentage of your outstanding balance each month, and it does not reduce your balance. Total interest paid over 30 years on a $300K loan at 6.11% is about $348,000 — more than the original loan amount.
Can I export my amortization schedule?
Yes. Click the Export CSV button after generating your schedule to download a complete spreadsheet-ready file with all monthly payment details including date, payment, principal, interest, extra payment, and remaining balance. You can open this in Excel, Google Sheets, or any spreadsheet program.
Does paying bi-weekly instead of monthly save money?
Yes — significantly. Making half your monthly payment every two weeks results in 26 half-payments per year, equivalent to 13 full monthly payments instead of 12. That one extra payment per year reduces a 30-year mortgage by about 4–5 years and saves tens of thousands in interest. Our bi-weekly mortgage calculator shows the exact savings.

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