Leave your details and we'll call you back
We can call you at a time that suits you.
Mortgage interest calculator. It is one of the most searched terms by anyone in the initial stages of buying a home in Ireland and for good reason. Before you start booking viewings, making offers, or even applying for an AIP, you need a realistic sense of what a mortgage will cost you every single month. Not a rough guess. A real number you can hold against your income and outgoings to see if this is doable.
This guide explains how Irish mortgage repayment calculators work, what the numbers mean, what the bank-specific calculators are not telling you, and how to use a repayment calculator to make smarter decisions. This can be for whether you are buying for the first time, moving, or thinking about switching.
How Your Monthly Repayment Is Calculated
Every mortgage calculator in Ireland, whether you are using the AIB mortgage repayment calculator, the EBS repayment calculator, the PTSB mortgage calculator, or an independent tool. It uses the same formula. It is the standard capital-and-interest amortisation formula:
Monthly Repayment = P × [r(1+r) ⁿ] ÷ [(1+r) ⁿ − 1]
Where P is your loan amount, r is the monthly interest rate (your annual rate divided by 12), and n is the total number of monthly payments (your term in years multiplied by 12).
What this produces is a fixed monthly figure that covers both interest and capital repayment, though the split between them shifts over time. In your early years, most of each payment goes toward interest. As your balance reduces, more goes toward paying down the actual loan. This is an amortising structure, and it is how every mainstream mortgage in Ireland works.
For example, on a €300,000 mortgage at 3.5% over 30 years, your monthly repayment is approximately €1,347. For a typical buyer considering a €300,000 mortgage, monthly repayments may fall between €1,400 and €1,800 depending on the mortgage rate and how long the loan runs. The rate and term are everything.
What to Put into the Calculator
Loan amount: This is your purchase price minus your deposit. If you are buying at €380,000 with a 10% deposit of €38,000, your loan amount is €342,000.
Interest rate: Use the rate you have been quoted or are comparing. As of May 2026, the lowest fixed rate available for a 90% LTV mortgage is a 4-year fixed rate of 3.1% with Bank of Ireland on a qualifying BER-rated home, while the lowest variable rate for first-time buyers with a 10% deposit is 3.85% from Avant Money. Always use a live rate rather than an estimate.
Mortgage term: Most Irish mortgages run for 25 to 35 years. A shorter term means a higher monthly repayment but significantly less total interest paid over the life of the loan. A longer term reduces your monthly outgoing but increases the overall cost.
What the Calculator Does Not Show You
This is where most people get caught out. The monthly figure from a standard mortgage calculator is not the full picture of what your mortgage will cost you.
Mortgage Protection Insurance: Every lender in Ireland requires this as a condition of drawing down your mortgage. It is a life insurance policy that clears the outstanding balance if you die during the term. Typical monthly costs range from €20 to €60 or more depending on your age, health, and loan size.
Home Insurance: This is another lender requirement. Budget €300 to €600 per year.
APRC vs Headline Rate: The headline interest rate is not the actual cost. The Annual Percentage Rate of Charge (APRC) includes all fees and charges associated with the mortgage and is the figure the CCPC recommends using when comparing lenders. Bank of Ireland’s APRC on a typical variable-rate mortgage of €100,000 over 20 years includes a €150 valuation fee and a mortgage charge of €175 paid to Tailte Éireann.
Rate changes after your fixed period: If you take a 3-year or 5-year fixed rate, your repayment is only fixed for that period. When it expires, you revert to the lender’s standard variable rate unless you switch or re-fix. Any calculator that holds your rate constant for 30 years is not reflecting reality, which is always a factor in what you might pay when the fix ends.
Cashback offers: Several lenders, including PTSB, Bank of Ireland, and Avant Money, offer cashback on drawdown in 2026. This does not reduce your monthly repayment but does affect the overall value of the mortgage. Factor it into your comparison rather than treating the headline rate as the only variable.
The Bank Calculators — What You Should Know
Many Irish borrowers search specifically for the AIB mortgage repayment calculator, the EBS repayment calculator, or the PTSB mortgage calculator. These are all genuinely useful tools, but they only show repayments based on that specific lender’s products and rates. They are designed to give you a sense of affordability within their own offering, not to help you compare the full market.
The same goes for the AIB mortgage overpayment calculator, a handy tool for existing AIB customers who want to see the impact of making additional payments, but not something that helps you assess whether a different lender might give you a better deal to begin with.
For a neutral, whole-of-market calculation, the CCPC mortgage comparison tool at ccpc.ie is the most comprehensive free resource available in Ireland. It shows rates, monthly repayments, total cost, and APRC across all regulated lenders in one place. It is without any commercial bias toward a particular bank.
How Rate Differences Play Out in Real Money
Small rate differences look insignificant on paper until you run the numbers over a full mortgage term.
On a €300,000 mortgage over 30 years, the cheapest first-time buyer rate available in early 2026 was Avant Money’s 3-year fix at 3.40%, producing repayments of approximately €1,330 per month. This is around €25 per month cheaper than the most expensive comparable option. Over the full 30-year term, that difference amounts to approximately €9,000.
That is before you factor in green mortgage discounts. For properties with a BER rating of B3 or better, green mortgage discounts of 0.1% to 0.3% off standard rates apply, with a 0.2% discount on a €300,000 mortgage saving approximately €10,000 over 25 years.
Using a Calculator at Each Stage
Before applying: Use a calculator to understand what monthly repayment you can comfortably sustain, then work backwards to set a realistic maximum loan and therefore a realistic property budget.
When comparing lenders, input the same loan amount and term at each lender’s current rate. Then check the APRC. Then look at what their reversion rate is when your fixed period ends. The cheapest rate today is not always the cheapest mortgage overall.
When considering overpayments: Most Irish lenders allow overpayments of up to 10% of the outstanding balance annually without penalty. Avant Money confirms that overpaying €35,000 on a 20-year €400,000 mortgage could reduce monthly payments by €233 (saving €12,500 in total interest) or reduce the term by 27 months (saving €29,500 in total interest). Run the numbers before you decide whether to save or overpay.
When considering switching: even a 0.5% rate reduction on a €300,000 mortgage saves meaningful money every month. Run your current rate and a competitor rate side by side to see whether the savings justify the effort of switching, and factor in any cashback available.
The Bottom Line
A mortgage interest rate calculator is one of the most useful tools available to any Irish homebuyer or existing mortgage holder, but it is a starting point, not a complete picture. Use it to model scenarios and build your intuition around how rate and term affect your repayments and total cost. Then look beyond the monthly number to the APRC, the reversion rate, overpayment flexibility, and any cashback on offer.
For a genuinely independent comparison across the full Irish market, including non-bank lenders like Avant Money, ICS Mortgages, Finance Ireland, and Moco that do not appear in individual bank calculators. Using a regulated mortgage broker costs you nothing and covers ground that no single bank’s calculator ever will.