Amortization Calculator

An amortization schedule is the full accounting of a loan: one row per payment, showing how much went to interest, how much reduced the balance, and what is left owing. Lenders generate one for every fixed-rate loan they write, and it answers questions a single monthly-payment figure cannot.

The mechanics are simple and repeat every month:

Interest this month = current balance × (annual rate ÷ 12)

Whatever is left of your payment after covering that interest reduces the principal. Next month the balance is smaller, so the interest charge is smaller, so more of the identical payment goes to principal. That shifting split is the entire story of amortization.

Work through the first two months of a $300,000 loan at 6% over 30 years, where the payment is $1,798.65:

• Month 1: interest is $300,000 × 0.005 = $1,500. Principal is $298.65. Balance: $299,701.35.
• Month 2: interest is $299,701.35 × 0.005 = $1,498.51. Principal is $300.14. Balance: $299,401.21.

You paid $3,597 across two months and reduced what you owe by $598.79. That ratio is uncomfortable to look at, and it is exactly why understanding the schedule changes behavior.

The crossover point — where principal finally exceeds interest in a single payment — arrives at month 223 on this loan, more than 18 years in. Until then, most of every payment is rent on the money.

Two practical uses for the schedule below:

• Find your true equity position. The balance column tells you when you cross 80% loan-to-value and can drop PMI, which is often years before people think to ask.
• Price an extra payment precisely. Adding to any payment removes all the future interest that principal would have generated. The schedule quantifies it: on the loan above, one extra $300 payment in month 1 saves about $1,500 in interest over the life of the loan.

Enter your loan details above to generate the full schedule, then toggle the extra-payment field to compare scenarios side by side.