Estimate monthly mortgage repayments
Use the Mortgage Repayment Calculator to compare repayments, interest, and overpayment scenarios.
Quick answer
- A repayment mortgage spreads the loan and interest across the full mortgage term.
- The three core inputs are mortgage amount, annual interest rate and term in years.
- A longer term usually reduces the monthly repayment but increases total interest.
- A higher interest rate can increase both the monthly repayment and total cost of credit.
On this page
The simple inputs behind the calculation
A mortgage repayment estimate starts with the amount borrowed, not the property price. If the property costs €350,000 and your deposit is €50,000, the mortgage amount is €300,000. The calculator then applies the interest rate and term to estimate the monthly payment needed to repay the mortgage over time.
Most Irish buyers use a capital-and-interest repayment mortgage. This means each monthly payment includes interest on the outstanding balance and a capital repayment that reduces the loan.
Mortgage repayment formula in plain English
The standard repayment formula converts the annual interest rate into a monthly rate, then spreads the loan over the number of monthly payments in the term. You do not need to use the formula manually, but understanding the inputs helps you judge the result.
Why interest is higher at the start
At the start of a repayment mortgage, the outstanding balance is high, so a larger share of the monthly payment goes toward interest. As the balance falls, more of each payment goes toward reducing the loan. This is why a repayment schedule or amortisation table can be useful.
Worked example
| Input | Example |
|---|---|
| Mortgage amount | €300,000 |
| Interest rate | 4.00% |
| Term | 30 years |
| Estimated monthly repayment | About €1,432 |
| Estimated total interest | About €215,609 |
This is an example only. Your actual repayment can differ depending on lender method, exact rate, repayment date, fees and mortgage terms.
Frequently asked questions
Is the mortgage repayment formula the same for every lender?
Most repayment calculators use the same broad formula, but lenders may calculate interest slightly differently. Always check lender illustrations before applying.
Does the calculator include mortgage protection?
No. Mortgage protection, home insurance, legal fees and other buying costs are separate from the monthly mortgage repayment.
Why does a longer term cost more overall?
A longer term spreads the loan over more months, lowering monthly payments but leaving the balance outstanding for longer, which usually increases total interest.
What is capital in a mortgage repayment?
Capital is the part of the payment that reduces the loan balance. Interest is the cost charged by the lender.
What is the best way to check my own repayment?
Use the Mortgage Repayment Calculator with your own mortgage amount, rate and term, then compare the result with lender quotes.
Is this guide tax advice?
No. It is general information for planning. Use official guidance or a tax adviser for your own situation.
Can I use the calculator for filing?
Use it as an estimate only. Complex activity such as DeFi, staking, mining, business trading, or many swaps may need specialist software or advice.
Sources & references
Key takeaways
- Mortgage repayments depend mainly on loan amount, interest rate and term.
- The property price is not the same as the mortgage amount because your deposit reduces the loan.
- More interest is paid earlier in the mortgage because the balance is higher.
- Calculator results are planning estimates, not mortgage approval.