Mortgage Amortization Calculator
Visualize how each payment splits between interest and principal, watch your equity grow year by year, and see the true cost of your loan. Free and private — nothing leaves your browser.
Amortization Visualizer
See equity build up over time.
How it works
Payment = Loan × r(1+r)^n / ((1+r)^n − 1), where r = monthly rate, n = monthsAn amortizing mortgage charges interest only on what you still owe. Every month your fixed payment first covers that interest; whatever is left reduces the balance. Because the balance starts large, early payments are mostly interest — on a fresh 5% loan, over 70% of the first payment is interest. As the balance shrinks, the same payment retires more and more principal, which is why equity growth starts glacial and finishes fast. The chart makes this crossover visible year by year.
Worked example
A €500,000 loan at 5% over 300 months costs €2,922.95 per month. Over the full term you pay about €876,900 — €376,900 of it interest, three-quarters of the loan amount again. After 10 of the 25 years you still owe roughly €366,000: only about a quarter of the debt is gone at 40% of the term. Overpaying early attacks the balance when interest has the most surface to feed on.
Frequently asked questions
Why does so little of my early payment reduce the loan?→
Each payment first covers interest on the remaining balance. Early on the balance is large, so interest eats most of the payment. As the balance falls, more of each identical payment goes to principal — that's amortization.
How is the monthly payment calculated?→
With the standard annuity formula: Payment = Loan × r(1+r)^n / ((1+r)^n − 1), where r is the monthly rate and n the number of months. A €500,000 loan at 5% over 300 months comes to €2,922.95/month.
How much interest will I pay in total?→
Often more than people expect: that same €500,000 loan costs about €376,900 in interest over 25 years. Shortening the term or overpaying early cuts the total dramatically because it shrinks the balance interest is charged on.
No black boxes — the exact formula is shown above · Last reviewed July 2026