How do lenders calculate maximum mortgage?

Most UK lenders use an income multiple of 4–4.5× gross annual income. They also stress-test affordability at a rate typically 3% above the product rate (often around 7–8% in 2025/26) to confirm you can afford payments if rates rise.

What is an LTV ratio?

Loan-to-Value (LTV) is the mortgage amount divided by the property value. A £225,000 mortgage on a £250,000 property is 90% LTV. Lower LTV generally means access to better rates and lower mortgage insurance costs.

11 / AFFORDABILITY

Mortgage Affordability Calculator

Find out what you can actually borrow — based on income multiples, monthly commitments, and a stress test at +3%. Includes LTV breakdown.

GuideHow affordability is assessed

Mortgage Planning Cluster

Use this hub to move from the core repayment formula into affordability, offset, overpayment, and rent-versus-buy comparisons without leaving the mortgage cluster.

Your Income

Your Annual Gross Income

Partner's Annual Income (optional)Leave at 0 if solo

Monthly Debt CommitmentsLoans, credit cards, car finance

Mortgage Details

Deposit / Down Payment

Interest Rate

Mortgage Term

years

Income Multiple (lender)Typical: 4–4.5x, max 5.5x

What You Can Borrow

Maximum Property Price

£287,500

Maximum Mortgage

£247,500

4.5x annual income

Monthly Payment

£1,376

Stress Test (+3%)

£1,829

can you afford if rates rise?

Loan to Value

Deposit 13.9% — £40,000

LTV 86.1%

Affordability Check

Monthly payment vs income

✓ 30% of monthly income

Stress test vs income

✓ 40% of monthly income

Deposit vs purchase price

✓ 13.9% deposit

Cluster Hubs

Use these organising pages when you want the main calculators and supporting guides for this topic grouped in one place.

Browse the mortgage calculators hubUse the main mortgage hub to compare affordability with repayment, rent-versus-buy, and deposit-planning pages.Open the overpayment and offset hubCompare spare-cash strategies once the base mortgage payment is clear.

Related Calculators

Move sideways to closely related calculators without leaving the same topic cluster.

Use the Mortgage RepaymentMonthly payment, total interest, and full cost over any term.Use the Offset MortgageHow savings reduce mortgage interest and shorten your term.Use the Mortgage OverpaymentInterest saved and years removed by paying extra each month.Use the Rent vs BuyLong-term financial outcome of renting against buying.

Related Guides

Use these supporting explainers when you need the formula, assumptions, or decision framing behind the numbers.

Read 10% vs 20% Deposit: What Changes in the Mortgage MathCompares the trade-off between buying sooner on a smaller deposit and waiting to reach a stronger deposit band that lowers borrowing and potentially improves pricing.Read Bigger Deposit vs Smaller Mortgage Payment: Which Side of the Equation Matters More?A decision guide for buyers comparing whether to wait and build a stronger deposit or accept a larger loan and a higher monthly payment now.Read How Much House Can I Afford on GBP100,000?A higher-income affordability example showing why a six-figure salary still does not create one universal home-price answer once deposit, debts, and lender stress are factored in.Read How Much House Can I Afford on GBP80,000?A salary-specific affordability example for an 80,000 income, showing why the final home-price range still depends on deposit, debts, and payment stress rather than income alone.