Loan Amortization Calculator
Enter any loan amount, interest rate, and term to instantly see your payment, total interest, and a complete payment-by-payment schedule. Works for mortgages, business term loans, auto loans, personal loans, and any fixed-rate installment debt. Supports monthly, bi-weekly, and weekly payment frequencies, plus extra payment modeling.
Free. No sign-up required.
Loan Details
Optional — accelerates payoff and reduces total interest
Monthly Payment
$1,996
Amortization Schedule360 monthly payments
| # | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | $1,996 | $246 | $1,750 | $299,754 |
| 2 | $1,996 | $247 | $1,749 | $299,507 |
| 3 | $1,996 | $249 | $1,747 | $299,258 |
| 4 | $1,996 | $250 | $1,746 | $299,008 |
| 5 | $1,996 | $252 | $1,744 | $298,756 |
| 6 | $1,996 | $253 | $1,743 | $298,503 |
| 7 | $1,996 | $255 | $1,741 | $298,248 |
| 8 | $1,996 | $256 | $1,740 | $297,992 |
| 9 | $1,996 | $258 | $1,738 | $297,734 |
| 10 | $1,996 | $259 | $1,737 | $297,475 |
| 11 | $1,996 | $261 | $1,735 | $297,215 |
| 12 | $1,996 | $262 | $1,734 | $296,953 |
How Loan Amortization Works
Amortization is the process of paying off a debt through equal, scheduled payments over a fixed period. Each payment is the same dollar amount, but what that payment covers shifts over time: early payments are mostly interest, later payments are mostly principal.
The math behind it: interest is charged on the current outstanding balance each period. Because the balance starts high, the interest charge is high, leaving little room in your fixed payment for principal. As you chip away at the balance, each period's interest charge falls — so more of each payment goes toward principal. It accelerates toward the end.
On a standard 30-year mortgage, roughly half your payments in the first decade go almost entirely to interest. In the final decade, almost every payment is principal.
The Payment Formula
The fixed periodic payment for a fully amortizing loan is:
- P — loan principal (amount borrowed)
- r — periodic interest rate (annual rate ÷ payments per year)
- n — total number of payments (term × payments per year)
Example: $300,000 at 7% for 30 years (monthly). r = 7% / 12 = 0.5833%, n = 360 payments. Monthly payment ≈ $1,996. Total paid over 30 years ≈ $718,000 — meaning $418,000 in interest on a $300,000 loan.
The Power of Extra Payments
Extra payments go 100% to principal — zero to interest. This has a compounding effect: a smaller balance means less interest accrues next period, which means more of the regular payment also goes to principal, which shrinks the balance faster, and so on.
| Extra/Month | Interest Saved* | Years Saved* |
|---|---|---|
| $100 | ~$26,000 | ~2.3 years |
| $200 | ~$48,000 | ~4.2 years |
| $500 | ~$96,000 | ~8.1 years |
| $1,000 | ~$148,000 | ~12 years |
* Approximate estimates for a $300,000 loan at 7% over 30 years. Use the calculator above for your exact numbers.
Monthly vs. Bi-weekly vs. Weekly Payments
Switching from monthly to bi-weekly doesn't just mean smaller payments more often — it means you make one extra full payment per year (26 half-payments = 13 full payments, not 12). That extra annual payment shortens a 30-year loan by roughly 4–6 years.
Monthly
12 payments/year. Simple and predictable. Aligns with most billing cycles and cash flow rhythms.
Bi-weekly
26 payments/year — the equivalent of 13 monthly payments. The most practical way to make an extra payment each year without feeling it.
Weekly
52 payments/year. Maximum principal reduction cadence. Best for borrowers paid weekly who want to minimize idle balance.
Frequently Asked Questions
Why does so much of my early payment go to interest?
Because interest is calculated on the remaining balance. When the balance is high at the start of the loan, more of each fixed payment covers interest, leaving less for principal. As the balance falls, so does the interest charge — and more of each payment reduces the loan itself. This 'front-loaded' structure is standard for all fixed-rate installment loans.
Does making extra payments actually save that much?
Yes — often dramatically. On a 30-year mortgage, even $100/month extra typically saves $25,000–$30,000 in total interest and cuts 2+ years off the loan. The savings are especially large early in the loan when the outstanding balance (and therefore interest charges) is highest. An extra payment made in year 1 saves far more than the same payment made in year 25.
What is the difference between amortizing and interest-only loans?
An amortizing loan has fixed payments that cover both interest and principal — the balance falls to zero by the end of the term. An interest-only loan (common in commercial real estate and some construction loans) requires only interest during the draw period; the full principal is due as a lump sum (balloon) at maturity. Interest-only is lower cash flow but leaves the full debt outstanding. This calculator handles fully amortizing loans.
Can I use this for a business loan?
Yes. Any fixed-rate, fixed-term installment loan uses the same amortization math — business term loans, SBA 7(a) loans, equipment financing, commercial real estate loans, and personal loans all work the same way. Enter the loan amount, your interest rate, and the loan term. For variable-rate loans, the schedule will shift as the rate resets, but this calculator gives you the baseline.
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This calculator uses the standard fixed-payment amortization formula. Results are for informational purposes only. Actual loan payments may vary based on lender fees, rounding, payment dates, and other factors. Consult your lender for exact payment schedules.