Mortgage Calculator Ireland

What this mortgage calculator tells you

A mortgage is usually an amortising loan: each monthly repayment contains both interest and capital. Early in the term, a larger share of the repayment goes towards interest; later, more of it goes towards reducing the balance.

This calculator estimates three things from the mortgage amount, annual interest rate and term you enter:

• the monthly repayment;
• the total interest paid if that rate remained unchanged for the full term;
• the total of all scheduled repayments.

It is designed for scenario planning, not as a lender quote. Real mortgages can move between fixed and variable rates, include fees and incentives, and may be repaid early or switched.

Reading the extra mortgage outputs

The monthly repayment is still the main result, but a mortgage is easier to understand when you can see how the early years behave. The first-year interest and first-year principal figures split the first 12 scheduled payments into the amount that pays interest and the amount that actually reduces the balance.

The balance after five years is especially useful when comparing a five-year fixed period, thinking about a future switch, or estimating how much debt would remain if you sold. It assumes the entered interest rate stayed unchanged and every scheduled payment was made.

The +1 and +2 percentage-point stress figures are not lender stress tests and are not forecasts. They simply recalculate the same mortgage amount and term at higher rates so you can see how sensitive the monthly payment is. The repayment per €100,000 borrowed gives a quick scaling figure for comparing different mortgage sizes at the same rate and term.

Worked example: €300,000 over 30 years at 3.5%

Using the calculator’s default example of a €300,000 mortgage, a 3.5% annual rate and a 30-year term, the estimated repayment is about €1,347 per month.

If that rate stayed unchanged for all 30 years, total scheduled repayments would be about €484,968, of which roughly €184,968 would be interest.

That example is useful because it shows why the interest rate matters even when the difference between two rates looks small.

How the repayment is calculated

Compound uses the standard repayment-mortgage formula:

Monthly repayment = P × r ÷ (1 − (1 + r)^−n)

where:

• P is the mortgage balance;
• r is the monthly interest rate;
• n is the total number of monthly repayments.

The annual rate you enter is divided by 12 for the monthly calculation. The model assumes equal monthly repayments and a constant interest rate.

Real lenders may calculate interest daily and may use different conventions around payment dates, rounding and fees, so small differences from a lender illustration are normal.

Why a small rate change can matter

Mortgage balances are large and mortgage terms are long. That means a difference of even 0.5 percentage points can materially change both the monthly payment and the total interest.

Use the calculator to stress-test several rates rather than only the rate you expect to receive. For example, compare your scenario at the quoted rate, then again at +0.5% and +1.0%.

The CCPC specifically provides mortgage comparison tools because changes in interest rates can have a significant effect on repayment costs.

Fixed rate versus variable rate

A fixed-rate mortgage keeps the agreed rate unchanged for a specified period. This gives repayment certainty during that fixed period, but the rate may change when the fixed term ends.

A variable-rate mortgage can change over time. Your repayment may rise or fall if the lender changes the rate.

For that reason, the “total interest” result on this page should not be read as a forecast unless the rate genuinely stayed unchanged for the entire mortgage term.

If you are comparing a current mortgage with a new rate or lender, use the Mortgage Switch & Rate Change Calculator rather than relying only on this page.

Mortgage term: lower monthly repayment versus higher lifetime cost

Extending the mortgage term generally reduces the required monthly repayment because the same balance is spread across more months.

But a longer term also leaves the balance outstanding for longer, usually increasing total interest.

That creates an important trade-off:

• shorter term: higher monthly repayments, usually lower total interest;
• longer term: lower monthly repayments, usually higher total interest.

A longer term is not automatically wrong. Monthly affordability and resilience matter. The useful comparison is whether the lower payment is worth the additional lifetime interest in your own circumstances.

How much can you borrow in Ireland?

This calculator does not determine how much a lender will approve.

Under the Central Bank of Ireland’s current mortgage measures, first-time buyers are generally subject to a maximum loan-to-income ratio of 4 times gross income, while second and subsequent buyers are generally subject to 3.5 times gross income.

For principal-home purchases, the standard loan-to-value limit is 90%, meaning a minimum deposit of 10% in the ordinary case. Buy-to-let lending is generally limited to 70% LTV.

Lenders are permitted a limited amount of lending above the macroprudential limits, and lenders also apply their own affordability and credit assessments. So a Central Bank maximum is not the same thing as a mortgage approval.

Use the Mortgage Borrowing Calculator for the income/deposit limits and the Mortgage Affordability Calculator to compare those limits with a monthly-payment scenario.

Your deposit and the property price

The mortgage amount is only one part of the purchase.

If you are buying a €400,000 home with a €40,000 deposit, the mortgage required would be €360,000 before considering whether income and affordability rules support that borrowing level.

You can model that separately using the House Deposit Calculator.

Costs this calculator deliberately leaves out

The monthly repayment shown here does not include the other costs of buying or owning a home.

Depending on the transaction, those may include:

• stamp duty;
• legal and conveyancing fees;
• property valuation;
• survey or engineer’s report;
• mortgage protection;
• home insurance;
• moving and furnishing costs;
• management fees for some properties;
• lender fees or conditions attached to cashback offers.

Mortgage protection is generally required for a mortgage on your principal home, subject to specified exceptions. Citizens Information notes that the lender must generally make sure mortgage protection is in place before advancing a home mortgage.

For an upfront cash budget, use the House Buying Costs Calculator.

Mortgage protection is different from your mortgage repayment

Mortgage protection is a form of life assurance intended to repay the mortgage if the insured borrower dies during the term.

It is not the same thing as mortgage repayment protection, which is a separate product that may cover repayments for a limited period in certain circumstances such as illness or unemployment.

Neither is included in the repayment number generated above.

Overpaying a mortgage

If your mortgage allows it, paying extra capital earlier can reduce future interest because interest is then calculated on a lower outstanding balance.

The effect can be substantial over a long remaining term.

Use the Mortgage Overpayment Calculator to model an additional monthly payment and estimate the time and interest that could be saved.

Before overpaying a fixed-rate mortgage, check the mortgage terms because limits or break costs may apply.

APRC versus the interest rate entered here

The rate field on this calculator is the mortgage interest rate used to calculate repayments.

When comparing mortgage products, lenders may also quote an APRC — Annual Percentage Rate of Charge. APRC is designed to represent the overall annual cost of credit and can incorporate more than the headline borrowing rate.

A lower advertised interest rate does not therefore always mean the lowest overall cost once fees, incentives and rate structures are considered.

This calculator does not attempt to recreate lender-specific APRC calculations.

A sensible way to use this calculator

Rather than running one scenario, try a small set:

1. Enter the amount you expect to borrow and the term you are considering.
2. Run the quoted interest rate.
3. Increase the rate by 0.5% and 1.0%.
4. Compare a shorter term if the monthly payment remains affordable.
5. Check the result against your overall household budget, not just gross income.
6. Then model deposit, buying costs and borrowing limits using the related Compound tools.

This produces a much more useful picture than focusing only on the lowest monthly repayment.

Frequently asked questions

Is this calculator only for first-time buyers?

No. The repayment mathematics are the same regardless of buyer type. First-time-buyer status matters for borrowing limits and schemes, not for the amortisation formula itself.

Does the calculator include a deposit?

No. Enter only the mortgage amount you expect to borrow. Use the House Deposit Calculator if you want to work from a property price and deposit.

Does it include stamp duty?

No. Stamp duty is an upfront purchase cost rather than part of the standard mortgage repayment. Use the Stamp Duty Calculator for that figure.

Why is my lender’s repayment slightly different?

Differences can arise from payment dates, daily-interest calculations, rounding, fees, rate structure or the exact first repayment period.

Is a 30-year mortgage cheaper than a 20-year mortgage?

It will usually have a lower monthly repayment, but if the same interest rate applied throughout it would normally cost more in total interest because the debt remains outstanding for longer.

Can I use this calculator for a buy-to-let mortgage?

You can use it for a basic repayment illustration, but buy-to-let lending has different deposit rules and can have different product structures, rates and tax considerations. It should not be treated as a complete buy-to-let analysis.

Method and limitations

This calculator is an educational planning tool. It assumes a repayment mortgage, equal monthly repayments and an unchanged annual rate over the selected term.

It does not model future rate changes, lender fees, cashback, insurance, tax, payment holidays, arrears, restructures, early repayment charges or changing payment dates.

The Central Bank’s mortgage measures and lender criteria can change over time. The sources below were checked when this page was updated.