Amortization Calculator

Introduction

An amortization calculator helps you understand how a fixed-rate loan is repaid over time: how much each monthly payment is, how much goes to interest versus principal, and how the remaining balance falls to zero.

Enter loan amount, annual interest rate, and term. The tool computes your payment and shows a month-by-month schedule plus an interactive chart.

What is amortization calculator?

Amortization Calculator uses three inputs:

• Loan amount — total borrowed
• Annual interest rate (%) — yearly borrowing cost
• Loan term (years) — how long you repay

It estimates:

• Monthly payment — fixed payment each month
• Total interest — all interest paid over the full term
• Total payment — principal plus total interest

An interactive chart and month-by-month table show how repayment splits between interest and principal over time.

Understanding the chart lines

The chart shows two lines that track loan payoff progress.

1. Remaining balance (blue line)

What it shows: How much you still owe at the end of each month.

Why it matters: This line falls toward zero as the loan is paid off. Early months pay mostly interest; later months pay mostly principal.

2. Cumulative interest (green line)

What it shows: Total interest paid from the start through each month.

Why it matters: This line rises throughout the loan. Most interest is paid early when the balance is highest — a key insight for comparing loan costs.

How the monthly payment is calculated

The tool assumes a fixed monthly payment on a fully amortizing loan:

PMT = P × [r(1 + r)^n] / [(1 + r)^n − 1]

Where:

• P = loan amount
• r = annual rate ÷ 12 (monthly rate as a decimal)
• n = years × 12 (number of months)
• PMT = monthly payment

Each month:

• Interest = remaining balance × r
• Principal = payment − interest
• New balance = old balance − principal

If the rate is 0%, payment simplifies to P / n.

Equal monthly payment vs equal monthly principal

Not every loan uses the same repayment structure. This tool uses equal monthly payment (amortization / EMI): the total payment stays fixed, while the split between interest and principal shifts over time. Another common method is equal monthly principal (trả gốc đều): the principal repaid each month stays fixed, so the total payment falls as interest on the shrinking balance drops.

	Equal monthly payment (this tool)	Equal monthly principal
What stays fixed	Total payment each month	Principal each month
What changes	Principal rises, interest falls each month	Total payment falls each month
Early months	Lower total payment	Higher total payment
Total interest (same rate & term)	Higher	Lower — principal paid off faster
Common in	US, Europe, India, Japan, many mortgages	China, Vietnam, some Asian corporate loans
Try it	Amortization Calculator (you are here)	Equal Principal Calculator

Common Use Cases

• Estimating monthly payments for a mortgage, auto loan, or personal loan.
• Seeing total interest cost before borrowing.
• Comparing how a shorter term or lower rate reduces interest paid.
• Teaching how amortization shifts from interest-heavy to principal-heavy payments.

Best Practices

• Confirm whether your lender uses equal payment or equal principal — methods differ by country and product.
• Confirm whether your lender uses the same rounding rules for the final payment.
• Taxes, insurance, and fees are not included unless you adjust inputs manually.
• Extra principal payments are not modeled — this tool assumes fixed scheduled payments only.
• Treat outputs as planning estimates, not guarantees or financial advice.