How Much Mortgage Can You Afford?

Mortgage lenders use sophisticated affordability assessments that go far beyond simple income multiples. While the old rule of thumb suggested you could borrow 4-4.5 times your income, modern affordability calculations consider your entire financial picture including all monthly commitments, household expenses, and future rate changes.

The stress test is crucial to understand. Lenders must assess whether you can afford payments if interest rates rise significantly—typically testing at rates 3% above the product rate. This means if you apply for a mortgage at 5%, lenders check affordability at 8%. This stress test often becomes the limiting factor rather than your income multiple.

Existing debts have an outsized impact on borrowing capacity. Credit cards, car finance, student loans, and even phone contracts all reduce what you can borrow. Each £100 of monthly debt payments typically reduces your maximum mortgage by £15,000-25,000. Paying off or reducing these debts before applying can significantly increase your borrowing power.

Different lenders use different affordability models, which means the same applicant can receive vastly different offers from different lenders. Some lenders are more generous with certain income types or more lenient on specific expense categories. Knowing which lender suits your profile is essential for maximising your mortgage approval.