Mortgage overpayment calculator
What the loan really costs, and what one extra payment a month buys back in years and interest — for annuity, linear and interest-only repayment alike.
Repayment type
One equal payment every month for the whole term. The standard Indian EMI and the Dutch annuïteitenhypotheek. Early payments are mostly interest.
Monthly payment · EMI
€1.415
Adding €150 a month clears the loan 3y 11m early and saves €22.814 in interest — a guaranteed, risk-free return equal to your 3.6% rate.
€750
€665
Lifetime interest
€106.688
Total repaid
€356.688
Debt-free
September 2047
A mortgage is a liability like any other
Track the balance alongside everything you own and the payoff shows up in your net worth as it falls — no bank login, no credentials.
Three ways to repay the same loan
Most calculators only model the annuity — one equal payment for the whole term, known as the EMI in India and the annuïteitenhypotheek in the Netherlands. It is the most common structure, but it is not the only one, and the difference between them is worth real money.
Linear repays the same slice of principal every month, so the payment starts higher and falls steadily. Because the balance drops faster, the total interest is markedly lower than an annuity over the same term. The Dutch lineaire hypotheek works this way, and it suits anyone who can afford a heavier start.
Interest-only pays only interest, leaving the full principal due at the end. It is the cheapest month to month and by far the most expensive over the life of the loan — and it needs a plan for repaying the balloon. In the Netherlands (aflossingsvrij) new lending is capped at 50% of property value for this reason.
Why early overpayments are worth so much more
Interest is charged on the balance, so removing a euro from the balance today removes every future month of interest that euro would have accrued. Early in the term the balance is at its largest, which is exactly when an overpayment does the most work.
Look at the interest and principal split above. On a fresh annuity mortgage the majority of each payment is interest, and it takes years before the split flips. Overpayments skip that queue entirely: every extra euro goes straight at the principal.
One practical caveat — many lenders cap penalty-free overpayments, often at 10% of the balance per year. Check yours before building a plan around a large monthly extra.
Overpay or invest?
Overpaying earns you a guaranteed return equal to your mortgage rate. Investing might earn more, but might not, and the difference between guaranteed and probable is the whole question.
The honest comparison is your mortgage rate against your expected return after tax, adjusted for the fact that one is certain. At a 3.6% mortgage rate and a 6% expected return, investing looks better on paper — but the mortgage saving is risk-free, and in countries where mortgage interest is deductible the effective rate is lower still. Run the same money through the compound interest calculator to see both sides.
Common questions
Annuity (the standard Indian EMI and Dutch annuïteitenhypotheek) keeps one equal payment for the whole term, so early payments are mostly interest. Linear repays the same slice of principal every month, so the payment starts higher and falls — and costs considerably less interest overall. Interest-only pays interest alone and leaves the full principal due at the end: cheapest monthly, most expensive over the life of the loan.
Yes, and more than most people expect, because every extra payment removes all the future interest that balance would have accrued. The saving is largest early in the term, when the balance — and therefore the interest on it — is at its highest.
Compare your mortgage rate with the return you would realistically earn after tax. Overpaying is a guaranteed, risk-free return equal to your interest rate; investing may beat it but is not guaranteed. Many lenders also cap penalty-free overpayments each year, which is a practical limit worth checking before planning around it.
No. Mortgage interest deduction exists in some countries (hypotheekrenteaftrek in the Netherlands, for example) and not others, and the rules change often. Treat the interest figures as gross.
Any of the 31 NetWorthTrackr supports, which makes this usable for a euro, rupee or pound mortgage rather than assuming dollars.
No. Everything is calculated in your browser and nothing is sent to us.
Estimates only, not financial advice. Every figure is calculated in your browser from what you typed — nothing is sent to us and nothing is stored.All tools →