Loan Amortization Calculator

Loan amortization (why this calculator exists)

People search for an “amortization calculator” because they want more than a monthly payment. They want a clear answer to: How much interest am I paying? How fast does my balance drop? And what happens if I pay a little extra each month? This page is built around those real questions, with a schedule you can scan and sanity‑check.

The key idea: your payment is split into interest and principal. Early in the loan, interest usually takes a bigger share. Over time, more of the same payment goes to principal, and the balance starts to fall faster. That’s amortization in one sentence.

How to use this amortization schedule

Start with the basics: enter the loan amount, APR, and term. The calculator estimates the standard fixed payment. Then expand the schedule to see each month’s split: payment, principal paid, interest paid, and remaining balance. If the schedule makes sense, you can trust the monthly number; if it doesn’t, you’ll catch a typo before it costs you money.

If you add an extra payment, we apply it directly to principal each month. That reduces the balance sooner, which reduces future interest. Even small extras can shorten the loan term and save real dollars because interest is calculated on the outstanding balance.

Monthly payment formula (fixed-rate loans)

The standard fixed payment for a loan is based on the monthly rate and the number of payments. In plain English: the payment is chosen so the balance reaches zero exactly at the end of the term. The schedule then shows how that payment gets allocated each month.

Real loans can add complexity (origination fees, “odd days” interest, promotional periods), but the fixed‑rate model is still the most useful baseline for planning and comparison shopping.

Why paying extra works (and when it matters most)

Extra payments are powerful because they attack interest at the source: the balance. When your balance is lower, the next month’s interest charge is lower too. That means the same regular payment now has a larger principal component, so you accelerate payoff.

You’ll often see the biggest impact early in the loan because that’s when the balance is highest and interest charges are largest. If you’re deciding between “start extra payments now” versus “start later,” the math usually favors starting sooner, assuming it doesn’t create cash‑flow stress.

What to check before you send extra money

• Confirm principal-only application: ask the lender how to mark payments so extra goes to principal.
• Look for prepayment penalties: uncommon for many consumer loans, but worth confirming.
• Compare alternatives: if you have high‑interest debt (like credit cards), paying that first may save more.

A practical example

Suppose you borrow $25,000 at 7.5% APR for 5 years. The monthly payment is designed to fully repay the loan over 60 payments. Now add $50 extra per month. The schedule typically shows an earlier payoff date and noticeably less total interest, because each extra $50 reduces future interest charges.

FAQ