Rates & sources
Standard amortisation formulas used across UK lenders. Interest rates move daily — confirm with your lender or broker.
Source: Bank of England — Statistics — figures refreshed at the start of each tax year.
When to use this calculator
- Before comparing lenders, brokers, or repayment options.
- When you want to test how a different deposit, rate, or term changes affordability.
- When you need a quick estimate before using a formal quote or agreement in principle.
- When you are stress-testing your budget against a potential rate rise to see the impact on monthly payments.
- When you want to understand the full cost of borrowing — not just the monthly figure — before you commit.
A realistic New Zealand planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Annual Household Income (£)
NZ$70,000
Monthly Debt Payments (£)
6
Deposit Available (£)
NZ$150,000
Mortgage Interest Rate (%)
NZ$600,000
After entering these figures, focus on result first and then rerun the tool with a more cautious assumption to understand the realistic range of outcomes rather than relying on a single estimate.
How to read your results
Result
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This calculator estimates how much you may be able to borrow and the price range of homes potentially within reach, based on standard UK mortgage affordability rules. It applies a common income multiple — typically 4 to 4.5 times gross annual income — and adds your stated deposit to arrive at an indicative maximum purchase price. The result is a guide only; your actual borrowing limit will depend on a full lender affordability assessment that considers your credit history, monthly outgoings, number of dependants, and the specific mortgage product you apply for. Interest rates used for illustrative monthly payment figures do not represent a quote. Always speak to a qualified, FCA-authorised mortgage adviser before making any property purchase decisions.
Common mistakes
- !Mixing up loan amount and property value, which can distort affordability and LTV.
- !Using a headline rate but forgetting fees, insurance, taxes, or repayment type.
- !Testing only one term length instead of comparing the payment and total cost together.
- !Forgetting that a repayment mortgage and an interest-only mortgage produce very different monthly figures and total costs.
- !Not accounting for the impact of a rate revert after an introductory fixed period ends, which can sharply increase payments.
What to do next
- Run a second scenario with a higher rate or shorter term so you can see the downside clearly.
- Compare the result with an affordability or overpayment calculator before applying.
- Use the related guides below to understand trade-offs before you request live quotes.
- Note down the monthly payment and total interest for your two or three strongest scenarios so you have a clear comparison ready when you speak to a broker.
- Check whether making a modest overpayment each month would reduce total interest significantly — run the overpayment calculator next to find out.
Frequently asked
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End-of-article next steps
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