Income multiples are only the starting point
Most people have heard that lenders offer around four to four and a half times your annual income, sometimes up to five or five and a half times for certain professions or higher earners. That figure is a useful rule of thumb, but it's not what actually happens inside a lender's affordability model.
In practice, a lender takes your gross income, then runs it through a stress test that looks at your existing debts, any dependants, your council tax band, typical living costs, and how much you'd still be able to pay if interest rates rose further. Two people earning the same salary can be offered very different amounts depending on whether they have a car loan, two children in childcare, or a large credit card balance.
This is why two mortgage brokers can give slightly different answers for the same household. The multiple is a headline; the underwriting is where the real number gets decided.
What the latest house price and rate data means for buyers
HM Land Registry's House Price Index for May 2026 and recent Bank of England minutes both suggest a market that's stabilising rather than sharply rising or falling. That matters for affordability because when house prices grow faster than wages, the salary needed to buy a typical home creeps up even if mortgage rates stay flat.
At the same time, swap rates and the Bank's policy rate feed directly into fixed mortgage pricing. A move of even half a percentage point on a typical £250,000 loan can change monthly repayments by more than £70, which lenders factor into how much they'll let you borrow in the first place.
If you're planning a purchase this year, it's worth checking a current mortgage rate rise calculator alongside any affordability figure a lender or portal gives you, because a quote that was accurate three months ago may not be accurate today.
Deposit size changes your affordability more than people expect
A bigger deposit does two things: it reduces the amount you need to borrow, and it often unlocks a better interest rate because you move into a lower loan-to-value band. Both effects combine to increase what you can realistically afford.
For example, moving from a 10% deposit to a 15% deposit on a £280,000 property doesn't just reduce your loan by £14,000 — it can also shift you from a 90% LTV rate to a noticeably cheaper 85% LTV rate, which lowers your monthly stress-tested repayment and can increase your borrowing headroom further.
First-time buyers in particular sometimes underestimate how much a modest increase in deposit, perhaps through a family gift or a few more months of saving, changes the mortgage offer they end up qualifying for.
Working out your own realistic number
Rather than relying on a single multiple, it helps to build your own picture: gross household income, monthly debt repayments, number of dependants, and the deposit you actually have saved. From there, a mortgage affordability calculator can give a far more personalised estimate than a generic 'four and a half times salary' rule.
It's also worth running the numbers at a higher interest rate than today's best deals, since lenders build in a buffer and your own budget should too. If your finances only just work at today's rate, a renewal in two or three years' time at a higher rate could be uncomfortable.
Finally, don't forget the one-off costs that sit outside the mortgage itself — stamp duty, survey fees, solicitor costs and moving costs all reduce the cash you have left for a deposit or furnishing the new home.
Open the matching calculator, save the result in My Toolkit and compare it with the next decision in the same journey.
FAQ
Frequently asked questions
Short answers first. Open the question if you want the detail behind the result.
Is the four and a half times salary rule still accurate in 2026?
It's a reasonable starting estimate for many households, but actual offers vary based on debts, dependants and outgoings. Some lenders go higher for certain professions or larger deposits, while others offer less if you have existing credit commitments.
Does a mortgage rate rise affect how much I can borrow, or just my monthly payment?
Both. Lenders stress-test your ability to repay at a higher rate than the one you're actually offered, so if rates rise generally, the maximum amount they're willing to lend often falls too, not just your monthly cost.
How much does my deposit size really change what I can afford?
More than most people expect. A larger deposit reduces the loan amount and can move you into a cheaper loan-to-value band, which lowers your stress-tested repayment and can increase the total amount a lender will offer.
Should I use my own numbers or wait for a lender's official affordability check?
Both are useful. Running your own figures through a calculator first helps you understand your realistic budget before you view properties, but only a full lender assessment or agreement in principle gives you a number you can rely on for an offer.
Sources
External links open the official source used to review this guide.