Mortgage calculator – work out your monthly payment

How the calculator works out the payment

The calculator uses an annuity payment made at the end of each month. At a constant rate it stays the same for the whole term. Only its make-up changes:

• interest for the month is the outstanding balance × the annual rate ÷ 12,
• principal is the rest of the payment, which reduces the debt.

For a €100,000 loan at 4% over 20 years, the first payment is €605.98. Of that, €333.33 is interest and only €272.65 reduces the debt. As the balance falls, the interest share gradually shrinks.

The default rate is the median of the banks’ published conditional 5-year fixed rates in our overview. It’s not a market average or an offer for you. If you already have a bank’s offer, enter its rate.

A longer term: lower payments, more interest

Extending the term lowers the monthly payment because you repay the principal over a longer period. But you pay interest on a higher balance for longer.

€100,000 loan at 4%	Monthly payment	Total interest
20 years	€605.98	€45,435.28
25 years	€527.84	€58,351.05
30 years	€477.42	€71,869.51

The total interest only applies if the rate stays the same for the whole term. With a 3- or 5-year fixation, that’s just a scenario.

Note: a longer term doesn’t necessarily mean you can borrow more. For applicants aged 41 or over whose loan runs past age 65, a longer term reduces the permitted multiple of annual income. To see how much you could borrow, use the income-based calculator.

How the payment changes at a higher rate

A change from 4% to 5% is a rise of 1 percentage point. For a €100,000 loan over 20 years, the payment rises from €605.98 to €659.96, or €53.98 a month. That’s about 9%, not the 25% by which the rate itself increased.

The table under the result shows the payment at a rate 1 point lower and 1 and 2 points higher. It helps you judge whether you could manage a higher payment after the fixation period ends. If the fixation is shorter than the term, the bank also tests the payment at a rate 2 points higher, capped at 6%, when it assesses your application.

What the calculation leaves out

• the arrangement fee, property valuation and land registry fee,
• account charges and insurance, which may be conditions for a rate discount,
• differences in how a particular bank counts interest and rounds amounts.

That’s why the result isn’t the APRC. To compare the total cost of two offers, use their APRC and representative examples with the same amount and term.

Payment versus loan amount

This calculator answers the question of what your payment would be for a given amount. Whether a bank will lend you that amount depends on your income, expenses, existing debts and age. The income-based mortgage calculator assesses that using the NBS limits.