Finance 2026-05-03 4 min read By Konvertibly Team

Mortgage Affordability Calculator: How Much Can You Borrow?

Find out how much mortgage you can afford based on income, expenses, and lending multiples — and understand the stress tests lenders actually apply.

How Much Mortgage Can You Afford?

Mortgage affordability is determined by two factors: how much a lender will offer you (based on income multiples and credit assessment), and how much you can actually sustain monthly without financial stress. Both matter.

Income Multiple Method

Max mortgage ≈ gross annual income × 4 to 4.5 (UK standard)
Higher multiples (5–5.5×) available with excellent credit and large deposits

Example: £60,000 income → typically up to £240,000–£270,000 mortgage

Affordability Assessment (What Lenders Actually Check)

Modern lenders go beyond income multiples. They assess:

Net income after tax and pension contributions
Monthly committed expenditure (loans, cards, childcare)
Living costs estimates
Stress test: Can you afford payments if rates rise by 3%?

The 28/36 Rule (US Guideline)

Housing costs ≤ 28% of gross monthly income
Total debt payments ≤ 36% of gross monthly income

Example: £5,000 gross monthly income → max housing cost £1,400/month; max total debt £1,800/month

Deposit Size Affects Rates

5% deposit: highest rate, limited lender choice
10% deposit: broader choice, better rates
20%+ deposit: best rates, usually no mortgage insurance required
40%+ deposit: access to best-in-market rates

Calculate what you can borrow: Free Mortgage Affordability Calculator