Mortgage Affordability Calculator
Calculate how much you can borrow based on your income, deposit, debts, and monthly outgoings. Includes stress tests, income multiples, and full cost breakdown.
How mortgage affordability is calculated
UK lenders typically offer mortgages of 4 to 4.5 times your annual income, though some may stretch to 5x or more for higher earners. Joint applicants combine their incomes. Your deposit is added on top of your borrowing to determine the maximum property price.
Lenders also apply a stress test — checking whether you could still afford repayments if interest rates rose by 3 percentage points. Monthly outgoings such as childcare, student loans, and existing debts are factored in, as they reduce the amount lenders are willing to offer.
The affordability ratio (monthly mortgage payment as a percentage of take-home pay) is a key measure. Most financial advisors recommend keeping this below 35% to leave room for other costs and unexpected expenses.
Frequently asked questions
- How much can I borrow for a mortgage?
- Most UK lenders offer between 4 and 4.5 times your annual gross income. For example, on a £50,000 salary you could borrow £200,000–£225,000. Joint applications combine both incomes. Some specialist lenders may offer higher multiples for professionals or high earners.
- What is a mortgage stress test?
- A stress test checks whether you could still afford repayments if interest rates rose significantly — typically 3 percentage points above your actual rate. If you're borrowing at 4.5%, the lender checks you could afford payments at 7.5%. This is a regulatory requirement to protect borrowers.
- Does my deposit affect how much I can borrow?
- Your deposit doesn't directly change the income multiple, but a larger deposit means you need to borrow less. A 10% deposit on a £300,000 property means borrowing £270,000, while 20% means borrowing only £240,000. Larger deposits also unlock better interest rates.
- What percentage of my salary should go to mortgage payments?
- Financial advisors generally recommend that your mortgage payment shouldn't exceed 28–35% of your net monthly income. Above 35% is considered stretched — you may struggle with unexpected costs, maintenance, or interest rate rises.
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