Free Online Calculators
Monthly interest & principal breakdown โ table, chart & CSV export
This amortization calculator breaks down every monthly payment into its interest and principal components for the full loan term. It uses the standard annuity formula, where your payment stays fixed while the interest portion shrinks and the principal portion grows over time. Results include a detailed table, a visual chart, and a CSV export.
Whether you're planning to buy a home, finance a car, or take out a personal loan, understanding exactly where your money goes each month is one of the smartest financial moves you can make. Our Amortization Calculator gives you a full, month-by-month breakdown of every payment you'll make over the life of your loan โ showing precisely how much goes toward interest, how much reduces your principal, and what your remaining balance looks like at any point in time. With built-in support for extra payments (Sondertilgung), an interactive chart, and a downloadable CSV export, this tool puts complete transparency at your fingertips โ for free.
Amortization is the process of paying off a debt through regular, scheduled payments over time. Each payment you make is split into two parts: a portion that covers the interest charged on the outstanding balance, and a portion that actually reduces the principal โ the original amount you borrowed. In the early months of a loan, the majority of your payment goes toward interest. As time goes on and the principal shrinks, the interest portion decreases and more of your payment chips away at the balance itself. This shift is called the amortization curve, and seeing it visually often surprises first-time borrowers.
An amortization schedule is simply a complete table showing this breakdown for every single payment period from the first month to the last. It's an essential planning tool for anyone who wants to understand the true cost of borrowing and explore strategies to pay off debt faster.
Our calculator uses the standard fixed monthly payment formula used by banks and lenders worldwide:
Monthly Payment (M) = P ร [r(1+r)โฟ] / [(1+r)โฟ โ 1]
Once the fixed monthly payment is determined, each month's breakdown is calculated as follows:
If you add an extra payment in any given month, that additional amount is applied directly to the principal, which immediately reduces the balance. This ripples forward through every subsequent month โ lowering the interest charged, shortening the loan term, and potentially saving you thousands of dollars over the life of the loan.
Imagine you take out a $300,000 mortgage at an annual interest rate of 7% for 30 years. Your fixed monthly payment works out to approximately $1,996. In your very first payment, about $1,750 goes to interest and only $246 reduces the principal. By month 180 (the 15-year midpoint), the split is much closer โ roughly $1,400 in interest and $596 in principal. By the final months, nearly the entire payment is principal. Over 30 years, you'll pay approximately $418,527 in total interest โ more than the original loan amount. Seeing this in the amortization table makes a powerful case for extra payments or refinancing.
You finance a $28,000 car at 5% annual interest over 5 years. Your regular monthly payment is about $528. Now suppose you add an extra $100 per month toward the principal. The amortization calculator shows you'd pay off the loan in roughly 4 years and 4 months instead of 5 full years โ saving approximately $370 in interest and freeing yourself from that monthly payment nearly 8 months early. It's a small change with a meaningful impact, clearly illustrated in the side-by-side comparison.
You borrow $15,000 for a kitchen renovation at 9% annual interest over 3 years. The monthly payment comes to approximately $477. The amortization schedule shows that you'll pay around $2,172 in total interest over the 36 months. By reviewing the table, you spot that making one extra payment per year (essentially a 13th payment) could cut your repayment time by about 2โ3 months and save over $150 in interest โ small but satisfying progress toward becoming debt-free sooner.
Every monthly loan payment is divided into two components. The interest portion is the cost you pay the lender for borrowing the money โ calculated as a percentage of your remaining balance. The principal portion is the part of your payment that actually reduces the amount you owe. Early in a loan, interest dominates the payment. Over time, as the balance falls, more of each payment goes toward the principal. The amortization schedule makes this shift completely transparent month by month.
Extra payments โ sometimes called Sondertilgung in German financial contexts โ are applied directly to your loan's principal balance, bypassing the interest calculation entirely. Because the monthly interest charge is based on your remaining balance, reducing that balance faster means less interest accrues in future months. The cumulative effect can be significant: even $50 or $100 extra per month on a 30-year mortgage can shave years off the loan term and save tens of thousands of dollars in total interest paid.
Yes โ the standard amortization formula applies to virtually any fixed-rate installment loan, including mortgages, car loans, personal loans, student loans, and home equity loans. As long as the interest rate and payment schedule are fixed, this calculator will produce an accurate schedule. Note that adjustable-rate mortgages (ARMs) or loans with variable interest rates would require recalculation whenever the rate changes, as the formula depends on a constant rate throughout the term.