UK Mortgage Affordability Calculator
Explore a borrowing range from your chosen household-income multiples. An optional combined debt budget can cap the repayment illustration.
Rule year: 2026/27 · GBP · Sources checked
Illustrative upper borrowing amount
Illustrative gross-income multiples and constant mortgage rate. Zero optional budget means the range is not reduced for debt payments; debts still appear in the repayment comparison. No lender criteria, maintenance, living expenses, benefits, guarantees or approval. Deposit excludes buying costs such as SDLT.
For informational purposes only. This estimate is not financial advice, a tax return, a payroll calculation or a lender decision. See the supported circumstances and exclusions below.
How this calculator works
Income multiples give a starting illustration, not a credit decision. The lower and upper inputs are chosen by you and multiply combined annual gross income. Existing monthly debts are shown alongside mortgage repayments. If you supply a combined monthly debt budget, the amount left after existing debts provides an additional amortisation-based cap. Neither approach captures all household spending, credit history or a lender’s stress-testing policy.
Formula and rules
Income-multiple borrowing = household income × chosen multiple. Optional budget cap = max(0, combined monthly debt budget − existing debts) / monthly payment per £1 borrowed. Display the smaller of each multiple result and the optional cap.
Assumptions and limitations
Illustrative gross-income multiples and constant mortgage rate. Zero optional budget means the range is not reduced for debt payments; debts still appear in the repayment comparison. No lender criteria, maintenance, living expenses, benefits, guarantees or approval. Deposit excludes buying costs such as SDLT.
Worked example
Combined income of £70,000 at chosen multiples of 3.5 and 4.5 gives £245,000–£315,000 before an optional repayment-budget cap. Adding £50,000 deposit produces property-budget illustrations of £295,000–£365,000, excluding purchase costs.
- Illustrative upper borrowing amount
- £315,000.00
- Illustrative lower borrowing amount
- £245,000.00
- Lower property budget including deposit
- £295,000.00
- Upper property budget including deposit
- £365,000.00
Official sources and review
Reviewed against the sources below on 2026-10-06. Rates are held in versioned rule modules. Versioned rules, official source review and year-specific calculation tests.
- MoneyHelper: How much can you borrow? ↗
Income multiples are illustrative; lenders also assess spending, credit history and affordability.
Common questions
Is 4.5 times income a guaranteed loan?
No. The multiplier is an editable illustration. Actual underwriting also considers spending, debts, credit, property details and lender policy.
How do debts affect the range?
They appear in the monthly commitment comparison. When you enter a combined debt budget, existing debts reduce the amount available for mortgage payments and can cap the range.
Does the deposit include Stamp Duty?
No. It is assumed available for the property price. Budget separately for purchase taxes, fees, moving costs and reserves.