About Loan Amortization Calculator

Generate detailed amortization schedules with principal/interest breakdown. Part of the DevTools Surf developer suite. Browse more tools in the Calculators collection.

Use Cases

• Generate printable payment schedules to share with co-borrowers
• Model the impact of refinancing at a lower interest rate
• Calculate break-even point when comparing 15-year vs 30-year loans
• Determine how much principal has been paid at any point in the loan

Tips

• Toggle 'Extra payment' to see how a monthly overpayment shortens the loan term and reduces total interest
• Switch between monthly and bi-weekly schedules — bi-weekly payments result in one extra full payment per year
• Export the full schedule as CSV to model scenarios in a spreadsheet or share with a lender

Fun Facts

• The word 'amortization' comes from Old French 'amortir' (to kill) — the idea being that each payment slowly 'kills' the debt. The concept appears in English legal texts as early as 1490.
• A 30-year fixed mortgage at 7% results in paying roughly 2.4x the principal in total payments. At 4%, that ratio drops to about 1.7x — illustrating how sensitive total cost is to rate.
• The US 30-year fixed-rate mortgage is unusual globally. Most countries use shorter terms (10-15 years) with adjustable rates, reflecting different housing finance systems.

FAQ

Why do early payments go mostly to interest?

Interest is calculated on the outstanding principal each period. In early months, the balance is highest, so the interest portion of the fixed payment is also highest. As principal shrinks, the interest share falls.

What is the difference between amortization and depreciation?

Amortization applies to intangible assets and loans (spreading cost or debt over time). Depreciation applies to tangible assets. Both are accounting methods for allocating costs across periods.

Does an extra payment reduce the term or the monthly payment?

By default, extra payments reduce the remaining term — the monthly payment stays fixed but you pay off the loan sooner. Some lenders apply extras to next month's payment instead; confirm with your lender.