How Loan Calculations Work

A loan is one of the most consequential financial decisions you make — yet most people spend more time choosing a phone than evaluating their credit terms. The monthly payment figure banks advertise is designed to look manageable. The number they prefer you not focus on is the total amount repaid. Our calculator makes both numbers equally visible, because the gap between them is money that belongs to the bank, not you.

How Amortization Works: The Hidden Front-Loading

Fixed-rate loans use a system called French amortization: every monthly payment is identical, but the split between principal and interest shifts over time. In the early months of a 5-year loan at 6%, roughly 60% of each payment is pure interest. By the final year, that ratio inverts — you're mostly repaying principal. This front-loading is why paying extra in year 1 saves dramatically more than paying the same extra amount in year 4: you eliminate interest that would compound over the remaining term.

Interest Rate vs. APR: The Number Banks Bury

The nominal interest rate is used to calculate your monthly payment. The APR (Annual Percentage Rate) includes all fees, origination charges, and insurance products the lender bundles in — and is legally required to be disclosed. A loan advertised at 4.9% may carry an APR of 6.8%. This calculator uses the interest rate for precise amortization math; always demand the APR when comparing offers from different lenders to see the true cost.

Three Moves That Save You Real Money

  • Shorten the term: A €30,000 loan at 6% over 7 years costs €6,700 in interest. Over 5 years, just €4,800. That's €1,900 saved for a difference of only €180 more per month.
  • One extra payment per year: On a 5-year personal loan, adding one extra monthly payment per year cuts total interest by roughly 15–18% and shaves months off the end.
  • Refinance strategically: If rates drop by 1.5% or more after your first year of payments, refinancing can save thousands — use the remaining balance from the amortization schedule as your new principal.

Reading the Visual Analysis

The Breakdown chart reveals instantly how much of your total repayment funds the bank's profit versus your actual asset acquisition. A well-structured loan has an interest slice below 20% of total repayment. The Balance Over Time chart shows your equity curve — the steeper it bends downward in the early years, the better your loan terms.