Mortgage Affordability Calculator UK 2026

Most UK lenders cap residential lending at 4.5× combined gross annual income. Variations:

• 4.5×, the standard maximum for the majority of cases.
• 5×, usually requires a higher deposit (15%+ LTV) and clean credit.
• 5.5×, typically reserved for professionals (doctors, lawyers, accountants) or specialist lenders.
• 3-3.5×, what older affordability calcs used to use; some lenders still apply it at high LTVs.

The multiplier alone doesn't decide the loan, lenders also run an affordability calculation comparing monthly outgoings to your post-tax income, stress-tested at a higher rate.

The Financial Conduct Authority requires lenders to test affordability at a notional rate above the rate you actually pay, commonly the lender's standard variable rate plus around 1-3 percentage points. The exact figure varies by lender and moves with the base rate, so this calculator lets you set the premium yourself rather than assuming one: the default adds 3 percentage points to your input rate, giving a stress rate of 8.00%. If your monthly payment at that rate would push you over the lender's outgoings limit, they'll reduce the loan even if the multiplier says you qualify.

This is why borrowers near the limit often see lower offers than they expect, the stress test, not the multiplier, is the binding constraint.