Useful next calculations
When to use this calculator
- Before comparing mortgage products, brokers or repayment types.
- When you want to test how a different deposit, rate or term changes the payment.
- When you need a quick estimate before using a formal illustration or agreement in principle.
- When you are stress-testing your budget against a higher rate.
A worked example
These are the example figures the calculator opens with.
| Input | Value |
|---|---|
| Loan Amount (€) | €200,000 |
| Interest Rate (%) | 5.5% |
| Term (Years) | 25 years |
For those figures the calculator returns:
- Monthly payment: €916.67
- Total interest: €275,000.00
- Capital due: €200,000.00
How to read your results
Monthly Payment
Estimated monthly mortgage repayment under the rate, term and balance you entered. Compare it with a lender illustration before you apply.
Total Interest
Additional amount paid above the original principal during the term, using the rate you entered. Fees and early-repayment charges are not included unless you added them.
Method & assumptions
An interest-only mortgage means your monthly payment covers only the interest charged on the outstanding loan — the original capital remains unchanged throughout the term and must be repaid in full at the end. This calculator computes the monthly interest charge by applying the annual rate (divided by 12) to the full loan balance, which remains constant because no capital is being repaid. In practice, the interest rate on your mortgage will likely change over time as fixed or tracker periods end and you remortgage, so the real cost will fluctuate. The calculator does not model the performance of any associated repayment vehicle. lenders require a verified, independent repayment strategy before granting an interest-only loan; the financial regulator mandates regular contact between lenders and borrowers to monitor repayment plans throughout the mortgage term.
Common mistakes
- Mixing up loan amount and property value, which distorts affordability and LTV.
- Using a headline rate but forgetting fees, insurance or repayment type.
- Testing only one term length instead of comparing payment and total cost together.
- Treating the result as a lender decision rather than a planning estimate.
What to do next
- Run a second scenario with a cautious assumption so you can see the downside clearly.
- Compare the result with the related calculators below before making a decision.
- Check current local rules, eligibility and provider terms before applying or committing money.
- Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.