See exactly how each payment splits between principal and interest, month by month.
Results are estimates for planning purposes and are not financial, medical, or professional advice.
How to Use the Amortization Schedule Calculator
An amortization schedule breaks every loan payment into its principal and interest parts, showing how your balance shrinks over time. This calculator builds the payment-by-payment table instantly, so you can see the cost of borrowing before you sign.
- Enter the loan amount, the total principal you plan to borrow.
- Enter the APR as a percentage, for example 6.5 for 6.5 percent.
- Enter the loan term in years, such as 15 or 30 for a typical mortgage.
- Click Calculate for the monthly payment, total interest and total paid, plus a table with principal, interest and balance per payment.
Amortization Schedule Calculator Formula
The monthly payment uses the standard amortization formula. With P as the principal, r as the monthly rate (the annual rate divided by 12) and n as the total number of payments, the fixed payment is M = P × r × (1 + r)^n ÷ ((1 + r)^n − 1). Each month, interest equals the remaining balance times r, and the rest of the payment reduces the principal — so early payments are mostly interest and later ones mostly principal.
Example Calculation
Say you borrow 300,000 dollars at 6.5 percent for 30 years. The monthly rate is 0.065 ÷ 12, about 0.005417, and there are 360 payments, giving a monthly payment of 1,896.20 dollars. In month one, interest is 300,000 × 0.005417 = 1,625.00 dollars, so only 271.20 dollars reduces the principal. By the final payment the picture flips: 1,885.99 dollars goes to principal and just 10.22 dollars to interest. Across all 360 payments you pay 382,633.47 dollars of interest — more than the loan itself.
When Do Payments Become Mostly Principal?
Every schedule has a crossover point: the first payment where the principal portion beats the interest portion. On the loan above it arrives at payment 233 — about 19.4 years in. A 15-year term moves it to payment 53, about 4.4 years in, and cuts total interest to about 170,398 dollars. Watch the balance column to see it flip.
Frequently Asked Questions
What is loan amortization?
Amortization is paying off a loan through fixed periodic payments. Each payment covers the interest due plus a slice of principal, and a schedule lists every payment with its split.
Why is most of my early payment going to interest?
Interest is charged on the balance, which is largest at the start. As it falls, the interest portion shrinks and more of each payment attacks the principal.
How do extra payments change my amortization schedule?
Extra payments go entirely toward principal, lowering the balance faster, cutting interest in later months, and potentially shaving years off the loan term.
What is the difference between a 15-year and 30-year amortization?
A 15-year loan has higher payments but far less total interest. On a 300,000 dollar loan at 6.5 percent, the 30-year schedule costs 382,633.47 dollars in interest versus about 170,398 dollars on the 15-year schedule, with a 2,613.32 dollar payment.
Does this calculator work for car loans and personal loans?
Yes. The same amortization math applies to any fixed-rate installment loan. Just enter the loan amount, rate, and term in months converted to years.
When does my payment start going mostly to principal?
At the crossover point, when the interest portion drops below the principal portion. On a 300,000 dollar loan at 6.5 percent over 30 years, that is payment 233, about 19.4 years in.
What does the first payment of a loan look like?
Mostly interest. On a 300,000 dollar loan at 6.5 percent, the first 1,896.20 dollar payment splits into 1,625.00 dollars of interest and only 271.20 dollars of principal.
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