How much can you borrow? How much should you borrow? These are different questions - and the gap between the answers is where your financial safety lives.
Most UK lenders will offer between 4x and 4.5x your combined annual income as a maximum mortgage. Some lenders go up to 5x or 5.5x for higher earners or certain professions. This is a rule of thumb, not a guarantee - they'll also stress-test your finances against potential rate rises.
Your existing debts matter significantly. Car finance, personal loans, and credit card minimum payments all reduce how much a lender will offer. For every £100/month in committed debt payments, your borrowing capacity typically falls by around £10,000–15,000 depending on the lender.
Enter a mortgage amount and rate to see your estimated monthly repayment. Run this at the current rate and also at 2% higher - that's your stress test.
The lender will tell you the maximum. You decide the right amount. This is often the most important financial decision of the exercise.