Continue your plan
Useful next calculations
Rates & sources
This is a user-assumption planning model, not lender underwriting. UK lenders assess income, spending, commitments, credit and future-rate affordability under their own policies.
| Band / figure | Rate |
|---|---|
| Income assumption | entered by you |
| Spending + buffer | entered by you |
| Lender decision | not modelled |
Source: FCA — mortgage interest-rate stress guidance — check the linked guidance and any live quote before acting.
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.
Example: checking borrowing headroom before viewing homes
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
| Input | Value |
|---|---|
| Annual household income | £52,500 |
| Monthly fixed outgoings | £1,500 |
| Monthly safety buffer | £500 |
| Stress-tested mortgage rate | 5.75% |
Treat the maximum loan as an outer estimate. Re-run the calculation with higher monthly expenses and a higher interest rate, then compare the resulting payment with the amount you can sustain while still saving for repairs and other goals.
How to read your results
Payment-Supported Loan
The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.
Mortgage Payment Budget
The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.
Method & assumptionsAuthoritative sources
This planning calculator converts the monthly payment left after the spending and safety buffer you enter into a loan amount at the selected rate and term. It does not use a lender income multiple and does not replicate underwriting. The output is a payment-supported ceiling based solely on your assumptions, not an amount a lender has assessed as affordable.
Real lenders review income, debts, dependants, regular spending, credit history, loan-to-value and the effect of future rate rises under their own policies. Include all ongoing commitments and keep a realistic buffer rather than allocating every spare pound to a mortgage. Obtain a decision in principle from a regulated lender or mortgage adviser before relying on a borrowing figure.
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.
What to do next
- Repeat the estimate using a higher mortgage rate and all recurring credit commitments to create a cautious range.
- Turn the affordable loan into a monthly repayment using the mortgage calculator.
- Subtract the deposit, SDLT, conveyancing, survey, and moving costs from the cash available before setting a property budget.
Go deeper — 1 guide reference this calculator
Frequently asked
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