UK Mortgage Affordability Calculator
Find out how much you could borrow and what your monthly repayments would be — based on your salary, deposit, and standard lender income multiples.
How lenders calculate affordability
UK mortgage lenders primarily use income multiples to set a maximum loan amount. The most common multiple is 4.5 times your gross annual salary — so a £50,000 salary could support borrowing of up to £225,000. Some lenders, particularly for high earners or certain professions such as doctors, lawyers, and accountants, will lend up to 5 or even 5.5 times income. A small number of specialist products go higher still. Joint applications combine both applicants' incomes before applying the multiple.
Beyond the headline multiple, every lender regulated by the Financial Conduct Authority must carry out a detailed affordability assessment. This looks at your net income (after tax and NI), your monthly outgoings including existing debt commitments, and your committed expenditure such as childcare and travel. If your declared outgoings leave insufficient surplus after the mortgage payment, the lender may reduce the offer even if the income multiple is satisfied.
Stress testing — what it means for you
Since the FCA introduced its mortgage rules following the 2008 financial crisis, lenders have been required to stress test affordability at a higher notional rate — typically 3 percentage points above the initial rate. This means the lender calculates what your monthly payment would be if interest rates rose by 3%, and checks that your income would still cover it. This is why some applicants find they can pass the headline multiple but still receive a reduced offer: it is the stress test that is binding, not the income multiple.
Our calculator shows both your repayment at the entered rate and the stress-tested repayment so you can see the full picture before speaking to a lender or broker. For context, your monthly take-home pay is also shown, allowing you to compare the repayment against your actual net income.
What else affects how much you can borrow
Your credit score and credit history play a significant role — lenders use credit reference agencies to check for missed payments, defaults, CCJs, and high levels of existing debt. Existing monthly debt obligations such as car finance, personal loans, and credit card minimum payments reduce the amount available for a mortgage repayment, which directly reduces the maximum offer. Your employment status also matters: employees on permanent contracts are assessed differently from contractors or self-employed applicants, who typically need two to three years of accounts.
Deposit sizes and LTV thresholds
Your deposit determines your loan-to-value ratio (LTV) and has a direct impact on the interest rate you will be offered. With a 5% deposit (95% LTV) you can access only a limited range of products, typically at higher rates. A 10% deposit (90% LTV) widens your options meaningfully. At 25% deposit (75% LTV) you access the most competitive rates. Moving from 90% to 85% LTV by saving an extra 5% can save thousands in interest over the term. If you are a first-time buyer, use our stamp duty calculator to factor in SDLT on top of your deposit requirement.
Help to Buy and shared ownership schemes can reduce the deposit required and the loan size needed. Under shared ownership you purchase a share of a property (typically 25–75%) and pay rent on the remainder, which can make homeownership accessible at lower salary levels. Your salary calculator and take-home pay calculator can help you work out monthly affordability before you approach a lender. If you are considering a pay rise before applying, our pay rise calculator shows how additional salary affects your take-home and maximum borrowing. Use the net-to-gross calculator if you know your net income and need to establish your gross figure for a lender's form.
Related calculators
Use the salary calculator to confirm your gross and net pay before speaking to a lender. The take home pay calculator breaks your net monthly income down so you can assess repayment affordability. Our stamp duty calculator shows the SDLT you will need to budget for on top of your deposit. The net to gross calculator is useful if you know your net income and need to supply a gross figure on an application form. If you are planning a pay rise to improve your mortgage offer, try our pay rise calculator. Our pension calculator can help you understand the trade-off between pension saving and building your deposit faster.
Frequently asked questions
Most high street lenders use an income multiple — typically 4 to 4.5 times your gross annual salary. So on a £40,000 salary you might borrow between £160,000 and £180,000. Some specialist lenders offer up to 5 or 5.5 times income for certain professions or high earners. Lenders also apply an affordability stress test at a rate typically 3% above the initial rate to check you could still afford payments if rates rose. Existing debts and outgoings reduce the maximum offer independently of the multiple.
A stress test rate is a higher hypothetical interest rate — usually 3 percentage points above your actual mortgage rate — that lenders use to check you could still afford repayments if interest rates rose significantly. Since the Bank of England base rate changes over time, lenders want reassurance that borrowers are not stretched to the limit at current rates. If your income does not pass the stress test, the lender will reduce the maximum loan offer even if the income multiple is met.
The minimum deposit for most lenders is 5% of the property price (95% LTV). However, the best mortgage rates typically require a deposit of at least 25% (75% LTV). With a 10% deposit (90% LTV) you access a reasonable range of products. A 20% deposit (80% LTV) unlocks significantly better rates. Saving a larger deposit reduces monthly repayments and the total interest paid over the term — and reduces the loan amount needed relative to your income multiple.
Yes — salary sacrifice schemes such as pension contributions, cycle-to-work, or salary sacrifice car leasing reduce your contractual gross pay, which is the figure lenders typically use for affordability calculations. Some lenders will add back pension salary sacrifice when assessing affordability, but practice varies. Declare all salary sacrifice arrangements to your mortgage broker so they can find a lender whose policy treats your income most favourably.