How Much Mortgage Can I Afford? A First-Time Buyer's Guide

Working out how much mortgage you can afford is the essential first step in buying a home. It sets your budget, narrows your property search, and ensures you do not overextend yourself financially. This guide explains how lenders assess affordability, what deposit you need, the stress tests they apply, and all the additional costs first-time buyers often overlook.

How Much Mortgage Can You Get Based on Your Income?

Most UK mortgage lenders use an income multiplier of 4 to 4.5 times your annual gross salary to determine the maximum they will lend. For a single applicant earning £40,000, that means a maximum mortgage of £160,000 to £180,000. For joint applicants earning £40,000 and £35,000 (combined £75,000), the maximum would be £300,000 to £337,500.

Some lenders stretch to 5x or even 5.5x income for certain borrowers. Higher multipliers are sometimes available for higher earners (£75,000+ salary), professionals in stable careers (doctors, lawyers, accountants), or borrowers with large deposits (25%+). However, borrowing at the maximum multiplier leaves very little financial headroom, so most advisors recommend staying within 4x income.

What Do Lenders Look at Beyond Income?

Lenders do not rely solely on income multipliers. They conduct a detailed affordability assessment that examines your monthly outgoings: existing debts (credit cards, car finance, student loans), regular commitments (childcare, insurance), and living expenses. Even if the income multiplier suggests you can borrow £200,000, the affordability assessment may reduce this if your outgoings are high.

Stress testing is a critical part of this assessment. Lenders must check that you could still afford repayments if interest rates rise by 3% above the lender's standard variable rate. If your mortgage rate is 4.5%, the stress test checks affordability at 7.5%. This is why some applicants who appear to comfortably afford their desired mortgage are offered less than expected.

How Much Deposit Do You Need for a Mortgage?

The minimum deposit for most UK mortgages is 5% of the purchase price. However, a larger deposit significantly improves your options. At 10%, you access a wider range of lenders and better rates. At 15% to 20%, you unlock the most competitive rates on the market. Each 5% increase in deposit typically saves 0.1% to 0.3% on your mortgage rate.

On a £250,000 property with a 25-year mortgage, the difference between a 5% and 15% deposit could save you over £25,000 in total interest. Use our Compound Interest Calculator to see how those savings compound over time.

What Other Costs Should First-Time Buyers Budget For?

The deposit and mortgage are not the only costs. First-time buyers should budget for several additional expenses that can total £3,000 to £10,000 on top of the deposit:

Stamp duty. First-time buyers pay no stamp duty on properties up to £425,000. Above this threshold, you pay 5% on the portion between £425,001 and £625,000. Use our Stamp Duty Calculator to check your liability.

Solicitor or conveyancer. Legal fees for buying a property range from £1,000 to £2,500 including disbursements (Land Registry fees, searches, bank transfer fees). Get quotes from at least 3 solicitors.

Property survey. A basic homebuyer's report costs £300 to £600. A full building survey (recommended for older properties) costs £600 to £1,500. Skipping the survey to save money is one of the most expensive mistakes buyers make.

Mortgage fees. Some of the best mortgage rates come with arrangement fees of £500 to £2,000. Compare the total cost (rate + fee) over the deal period rather than choosing the lowest rate alone. Use our Home Affordability Calculator to model different scenarios.

How Can You Improve Your Mortgage Borrowing Power?

1. Pay down existing debts. Clearing credit cards and car finance before applying removes these from the affordability assessment and increases the maximum you can borrow.

2. Increase your deposit. A larger deposit means you need to borrow less and access better rates. Even an extra 5% can make a meaningful difference.

3. Get a Decision in Principle. This gives you a clear borrowing figure before you start viewing properties. It also strengthens your position when making an offer, as sellers know you are a serious buyer.