Mortgage affordability calculator
Turn your income and deposit into a realistic buying budget.
A rough ceiling, not an offer — lenders stress-test your outgoings, debts and credit history, so real criteria vary widely. Not financial advice.
The quick rule of thumb is 4.5 times gross annual income — a £40,000 salary supports roughly £180,000 of borrowing, a couple on £70,000 combined roughly £315,000. Regulators cap how much lending banks can do above 4.5×, so while some borrowers (typically higher earners with big deposits) get 5× or more, 4.5× is the sensible planning number. Add your deposit to the loan and you have a realistic ceiling price.
In practice lenders run a full affordability assessment, not just a multiple. Regular commitments — car finance, loans, childcare, maintenance payments — reduce the figure meaningfully: roughly speaking, £300 a month of committed spending can knock £20,000–£30,000 off what you can borrow. Variable income (bonuses, overtime, self-employment) is usually counted only partially, and often needs two years of history.
Two honest cautions. First, the maximum a lender will give you and the amount you should borrow are different numbers — a mortgage at the ceiling leaves nothing for rate rises or life changes, which is why lenders also stress-test the payment at a higher rate. Second, every lender’s model differs, sometimes by tens of thousands of pounds, so treat this as a planning estimate and get a decision in principle (a soft-check quote from a real lender) before you book viewings.
Common questions
How many times my salary can I borrow for a mortgage?
Most lenders will go to 4.5× gross income, and regulators limit how much of any lender’s book can exceed that. Some stretch to 5–5.5× for higher earners, professionals, or lower loan-to-values. Joint applicants combine incomes: two salaries of £30,000 and £25,000 give a base of around £247,500 at 4.5×.
What reduces how much I can borrow?
Committed monthly spending is the big one: car finance, personal loans, credit-card balances, childcare, school fees and maintenance all come off your assessed income. Recent credit problems, a short self-employment history and a small deposit also shrink offers. Clearing a £250-a-month car loan before applying can add £20,000 or so to what some lenders offer.
Does a bigger deposit mean I can borrow more?
Mostly it means you can borrow at better rates — pricing improves in steps at 90%, 85%, 80% and 75% loan-to-value. It raises your budget indirectly too: lower rates mean lower stressed payments, and a few lenders offer higher income multiples below 85% LTV. But the income multiple, not the deposit, remains the main ceiling.
Is a decision in principle a guarantee?
No. It is a lender’s estimate based on stated income and a soft credit check, useful for setting a budget and reassuring estate agents. The binding decision comes after full underwriting — payslips, bank statements, and a valuation of the specific property. Treat a DIP as a strong signal, not a promise.
Numbers are half the story. Check the home itself.
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