Loans, credit cards, childcare — not food/utilities.
FCA floor ~5.5–7.5%.
What is mortgage affordability?
Mortgage affordability is the amount a lender will consider letting you borrow. UK lenders use two checks and take the lower result. One is an income multiple, commonly up to 4.5 times gross income. The other is a stress test: they ask whether you could still afford the payment if the rate were higher, often around 7% to 7.5%, after your monthly commitments.
A high income with low outgoings is usually limited by the multiple. Heavy outgoings make the stress test the tighter limit. This calculator applies both checks to the income and spending you enter and shows which one binds. The result is an estimate of borrowing capacity, not a mortgage offer.
On a combined income of £45,000, a UK lender might offer up to £164,005 (4.5× income cap or stress-test, whichever is lower), supporting a property price of up to £204,005 at 80% LTV.
Which limit binds you?
UK lenders apply two caps and use the lower of the two. Here's what each says for your inputs.
How UK mortgage affordability works
Income multiple cap
Most UK lenders cap mortgages at 4.5× combined gross income. A few lenders offer 5.0× or 5.5× for high earners or professionals (doctors, lawyers, accountants).
- £50,000 sole income → £225,000 max loan (4.5×)
- £80,000 joint income → £360,000 max loan (4.5×)
- £120,000 joint income → £540,000 max loan (4.5×)
Stress-test cap
Lenders check you could still afford the monthly payment if interest rates rose. The stress rate is usually the product's revert rate + 3%, or a floor around 7–7.5%. Your monthly outgoings (loans, credit cards, childcare) reduce the income available for a mortgage.
We use a simplified UK tax approximation to estimate net monthly income. Individual lender models vary.
Frequently asked questions
How much can I borrow for a UK mortgage?
Most UK lenders cap mortgage borrowing at 4.5× your annual income (joint income if applying together). Some lenders go to 5.5× for high earners or professionals. The actual maximum also depends on whether you pass the lender's stress-test at ~7.5%.
What is the FCA stress-test rate?
Lenders must check you could still afford payments if rates rose to a stress rate — typically 3% above the revert rate, or a floor of around 7–7.5%. From August 2022, Bank of England-mandated stress testing was formally withdrawn but most lenders still apply their own internal stress rate.
Do my monthly outgoings affect how much I can borrow?
Yes. Credit cards, loans, car finance and childcare all reduce the income a lender considers available for a mortgage. This calculator includes your monthly outgoings in the stress-test limit.
Does the deposit affect affordability?
Deposit sets your LTV (loan-to-value) and unlocks different rates, but it doesn't change how much you can borrow — that's driven by income and outgoings. A bigger deposit buys you a pricier home at the same loan amount.
Why does this estimate differ from a lender's decision in principle?
Lenders use bespoke affordability models with many variables (ONS spending data, dependants, location). This tool gives a realistic ballpark using the two most common caps — income multiple and stress test — but a real DIP will vary.
Reviewed by the Mortgage118 editorial team. Affordability parameters reflect typical UK high-street lender practice. This calculator provides an estimate only and does not constitute mortgage advice.
- Income multiple
- 4.5×
- Stress rate (default)
- 7.5%
- Default rate
- 4.6%
- Tax estimate
- Basic-rate approximation
Estimate only — individual lenders use their own affordability models.