Tool 07 · Loan & mortgage
What will this loan really cost?
Every loan has a sticker price and a true price — the interest on top. Set the amount, rate and term to see your monthly payment, the total you'll repay, and watch the balance melt away.
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Pro features. Model overpayments, read insights, see the amortization schedule, compare terms and export.
Pay it off faster
Refine the model
Overpay each month to clear the loan early and cut interest.
A lump sum today knocks straight off the balance.
Year by year (amortization)
Compare terms
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How the loan & mortgage calculator works
A repayment loan is paid off in equal monthly instalments. Each payment covers the interest due that month first, and whatever is left chips away at the principal (the amount you borrowed). Early on, most of your payment is interest; as the balance falls, more goes to principal — which is why the balance drops slowly at first, then faster. This is called amortization.
The monthly payment is fixed by three numbers: the amount, the interest rate (APR) and the term. This tool computes it with the standard amortization formula, then shows the total you’ll repay and how much of that is pure interest. In Pro, adding a regular overpayment or a one-off lump sum shortens the term and can save a surprising amount of interest.
The headline interest rate hides the real story. On a long loan like a mortgage, the total interest you pay can rival — or even exceed — the amount you borrowed, simply because you’re paying it over decades. Seeing that number in black and white is often the nudge people need to shop harder on the rate, choose a shorter term, or overpay. Small changes to any of the three inputs move the total by thousands.
A worked example
€250,000 mortgage · 5% APR · 30-year term
The monthly payment is about €1,342, and over 30 years you repay roughly €483,000 — of which €233,000 is interest, nearly as much as the house itself. Overpay by just €200 a month and you clear it about seven years early and save tens of thousands in interest, because every extra euro comes straight off the principal.
Things to keep in mind
- Overpay early for maximum effect. Extra payments in the first years remove principal that would otherwise have generated interest for the whole term — the earlier, the bigger the saving.
- Shorter term vs lower payment. A shorter term means higher monthly payments but far less total interest. Use the Pro term comparison to see the trade-off for your loan.
- This excludes fees, taxes and insurance. A mortgage in particular carries arrangement fees, property tax and buildings insurance that aren’t in the repayment maths.
- Check for overpayment limits. Some fixed-rate loans cap penalty-free overpayments (often 10% a year); confirm your terms before front-loading payments.
Frequently asked questions
Should I overpay my mortgage or invest instead?
It’s a classic trade-off. Overpaying gives a guaranteed, risk-free "return" equal to your mortgage rate; investing might return more but carries risk. As a rough guide, if your expected after-tax investment return comfortably beats your mortgage rate, investing can win — but many people value the certainty and peace of mind of clearing debt.
Is a 15-year or 30-year mortgage better?
A 15-year loan costs much less interest overall and builds equity faster, but the monthly payment is significantly higher. A 30-year loan is more affordable month-to-month but far more expensive in total. Enter both terms in the compare table to see the exact numbers for your amount and rate.
Why is so much of my early payment interest?
Interest is charged on the outstanding balance, which is largest at the start. So in the first years most of each payment is interest and little reduces the principal. Overpaying early is powerful because it cuts the balance that all future interest is charged on.
Does overpaying really save that much?
Often yes. Because every extra amount comes straight off the principal, it removes all the future interest that balance would have generated. Try the "Extra per month" slider in Pro to see the months and interest saved.
Is this a mortgage calculator too?
Yes — a mortgage is just a large amortizing loan. Enter the mortgage amount, rate and term. Note it doesn’t include taxes, insurance or fees, which vary by lender and location.