Mortgage Affordability Calculator
See realistically how much you could borrow and the property price you can target, based on income, deposit, debts and the rate you'd be offered.
Your estimated buying power
Tell us your income and deposit, and we'll show your rough buying power.
How it works
What this calculator does. It estimates the maximum mortgage you could comfortably afford, and adds your deposit to suggest a realistic property price to target. Unlike pure income-multiple tools, it works from affordability — what's left of your income after debts, and how much of that you're willing to commit to housing.
How the calculation works. We start with your gross monthly income and subtract your existing monthly debt payments (car finance, credit cards, student loans). Your chosen comfort ratio — the share of remaining income you're happy to spend on the mortgage — gives a target monthly payment. We then reverse the standard repayment formula at your interest rate and term to find the largest loan that produces that payment. Adding your deposit gives the property price.
A worked example. Take a household earning £60,000 a year (£5,000 a month) with £200 of monthly debt payments, a £30,000 deposit, a 5.5% interest rate, a 25-year term and a 35% comfort ratio. Affordable monthly housing budget: 35% × £5,000 − £200 = £1,550. At 5.5% over 25 years that supports a mortgage of around £252,000, so with the deposit you could target a property around £282,000.
Why this matters. Knowing your realistic ceiling before viewing properties stops you falling for places you can't sustainably afford, and gives you a clear brief for estate agents and brokers. It also lets you stress-test the decision: re-run the calculation 1–2% above your offered rate and check the result still fits — that's roughly how UK lenders test affordability since the 2014 mortgage rules.
When to use it / when not to. Use it in early planning, before applying for an Agreement in Principle, and whenever your income, debts or rate expectations change. Don't treat the result as a guaranteed offer — lenders also look at credit history, employment type, deposit source and the property itself.
Common mistakes. Entering net (take-home) income instead of gross; forgetting to include credit card minimum payments and car finance; using today's low rate without stress-testing for rises; and ignoring running costs like service charges, ground rent and insurance, which sit on top of the mortgage payment.
Frequently asked
Complete Guide
Rent vs Buy in the UK: Key Financial Considerations
The 'renting is dead money' line is one of the most repeated phrases in UK personal finance — and one of the most misleading. Whether buying or renting works out better for you depends on your deposit, how long you plan to stay, mortgage rates, and what you'd do with the money you didn't tie up in a home.
What renting really costs
When you rent, you pay for somewhere to live and the flexibility to move. You don't pay buildings insurance, major repairs, or stamp duty, and you can leave at the end of a tenancy without estate agent fees.
The trade-off is that your housing costs can rise at renewal, and you're not building any equity in the property.
What buying really costs
A mortgage payment is only part of the cost of owning. You'll also have stamp duty, legal fees, surveys, buildings insurance, maintenance, service charges (on leasehold flats), and sometimes ground rent.
Over a 25-year mortgage you'll typically pay a significant amount in interest on top of the price of the home — which is why overpayments, when affordable, can be so powerful.
The break-even question
Buying tends to win financially the longer you stay put, because the upfront costs (stamp duty, fees, moving) get spread over more years. As a rough guide, if you might move within 3–5 years, renting often comes out ahead once costs are honest.
Our rent vs buy calculator lets you compare the realistic monthly cost of each, factoring in the deposit you'd otherwise invest.
Beyond the spreadsheet
Money isn't the only factor. Owning gives you security of tenure and the freedom to decorate; renting gives you flexibility to follow work or relationships without selling up.
There's no universal right answer — only the one that fits your life and your numbers today.