Mortgage Repayment Estimator
Use this compare the market mortgage calculator style tool to estimate your repayments before you apply. Enter your details below and click calculate.
How this compare the market mortgage calculator helps
When you start house hunting, the monthly payment is usually the number that determines what is realistic. A compare the market mortgage calculator gives you a quick estimate so you can understand affordability before speaking with a lender or broker. It does not replace formal advice, but it can make your planning far more accurate.
This page focuses on practical budgeting: purchase price, deposit, interest rate, loan term, and repayment type. By adjusting just those values, you can see how much your payment can rise or fall. That clarity can save you from over-borrowing and help you compare options with confidence.
What the calculator includes
- Loan amount: Automatically estimated as property price minus deposit.
- Repayment methods: Standard repayment and interest-only scenarios.
- Payment frequency: Monthly, fortnightly, or weekly payment estimates.
- Total interest: Useful for understanding long-term borrowing cost.
- Optional annual fees: A simple way to include product or admin fee assumptions.
Step-by-step: using the calculator well
1) Start with realistic property and deposit numbers
It can be tempting to test dream numbers first, but it is more useful to begin with your likely price range and the deposit you can genuinely access. If your deposit is 10% instead of 20%, your monthly cost can change significantly due to a larger loan balance and potentially higher rates.
2) Test different rates, not just one
Interest rates can move. Even if today’s offer looks attractive, stress test your budget at a higher rate. Many buyers run at least three scenarios:
- Current likely rate
- +1% buffer rate
- +2% stress rate
If all three fit comfortably inside your monthly budget, you are usually in a stronger position.
3) Compare terms and repayment structures
A 35-year mortgage may lower monthly payments, but total interest often rises. Interest-only can reduce regular payments further, but the original balance still needs to be repaid later. Use the calculator to compare the trade-off between short-term affordability and long-term cost.
Repayment vs interest-only: what changes?
In a repayment mortgage, each payment covers both interest and part of the principal. Over time, your balance drops to zero by the end of the term (assuming all scheduled payments are made).
In an interest-only mortgage, regular payments only cover interest. The original principal usually remains outstanding until the term ends. That can improve cash flow now, but you must have a credible repayment plan in place for the final balance.
- Repayment: Higher monthly payments, lower end-of-term risk.
- Interest-only: Lower monthly payments, larger future repayment responsibility.
How to compare mortgage deals more effectively
A compare the market mortgage calculator is best used alongside rate shopping. When you review multiple products, do not focus on the headline interest rate alone. Include:
- Arrangement or booking fees
- Early repayment charges
- Reversion rate after an introductory period
- Flexibility for overpayments or payment holidays
Two mortgages with similar rates can have meaningfully different total costs once fees and flexibility are considered.
Common budgeting mistakes to avoid
Ignoring ownership costs beyond the mortgage
Mortgage payments are only one part of homeownership. Also plan for council tax, insurance, maintenance, utilities, and emergency repairs.
Choosing the maximum loan available
Borrowing up to lender limits can leave little room for life events. A safer strategy is to keep some monthly margin for savings and unexpected expenses.
Not running a stress test
Even fixed deals end. Test affordability under a higher post-fix rate so you are better prepared for remortgaging periods.
Quick FAQ
Is this calculator exact?
No. It provides an estimate using standard amortisation formulas. Your lender may calculate differently and include additional product-specific costs.
Can I use it for buy-to-let?
You can estimate payments, but buy-to-let underwriting often uses rental coverage tests and different criteria. Treat results as indicative only.
Why does a longer term reduce monthly cost?
Because repayment is spread over more months. However, total interest often increases, so lower monthly payments can mean a higher long-term cost.
Should I include fees?
Yes. Adding annual or recurring fee assumptions gives a more realistic picture of your total borrowing cost.
Final thoughts
The most useful way to use a compare the market mortgage calculator is to run multiple scenarios and compare outcomes side by side. Focus on both monthly affordability and total long-term cost. If a deal still looks strong after stress testing, you are making decisions from a much safer foundation.
Disclaimer: This calculator and article are for educational purposes only and do not constitute financial advice.