Estimate how much you could borrow based on your income, expenses, and lender stress tests.
This calculator provides estimates for guidance only. It does not constitute financial advice. Actual lending criteria vary by lender. Always consult a qualified mortgage adviser before making financial decisions.
Before you start browsing property listings, it is essential to know how much you could realistically borrow. UK mortgage lenders use a combination of income multiples and affordability stress tests to determine your maximum loan. Simply multiplying your salary by 4.5 gives a rough figure, but the reality is more nuanced because lenders also consider your monthly outgoings, existing debts, and whether your finances could withstand a significant interest rate rise. This mortgage affordability calculator applies both the standard income multiple approach and the Financial Conduct Authority (FCA) stress test to estimate your maximum borrowing. The stress test adds 3 percentage points to the current rate and checks that the resulting payment stays within an affordable threshold. By entering your income, partner income (for joint applications), monthly expenses, and deposit, you can see a realistic borrowing limit and total property budget. The calculator also shows what your monthly payment would be at the actual rate and at the stress-tested rate, giving you a clear picture of the financial commitment involved.
To estimate your mortgage affordability: 1. Enter your annual income before tax. This is your gross salary or primary income source. 2. If applying jointly, enter your partner's annual income. For single applications, leave this at zero. 3. Enter your monthly committed expenses. Include loan repayments, credit card minimum payments, childcare costs, and any other regular financial commitments. Do not include rent (as this will be replaced by the mortgage) or general living costs. 4. Enter your available deposit. This is the cash you can put toward the property purchase upfront. 5. Set the expected interest rate. Use the rate currently offered by lenders for your deposit size and loan-to-value ratio. The default of 5.5% reflects typical UK rates but adjust to match your situation. 6. Choose your preferred mortgage term using the slider. Standard UK terms are 25 to 35 years. 7. Review the results. The calculator shows your maximum borrowing, total property budget (borrowing plus deposit), monthly payment, stress test payment, income multiple, and the proportion of your income that goes toward the mortgage.
The calculator uses two methods to determine maximum borrowing, then takes the lower of the two: Income Multiple Method: Maximum borrowing = (annual income + partner income) x 4.5. This is the standard multiplier used by most UK high-street lenders. Some specialist lenders may offer up to 5x or 5.5x for certain professions. Stress Test Method: The FCA requires lenders to check that borrowers can afford payments at a stressed rate. The stress rate is the actual interest rate plus 3 percentage points. The maximum monthly payment at the stressed rate must not exceed 45% of gross monthly income, minus committed expenses. Using the annuity formula in reverse: P = M x [(1+r)^n - 1] / [r x (1+r)^n], where M is the maximum affordable monthly payment, r is the stressed monthly rate, and n is the total number of payments. This gives the maximum borrowing that keeps the stressed payment affordable. The calculator then takes the lower of the two results. If the stress test produces a lower figure than the income multiple, it means your expenses or the interest rate environment constrain your borrowing below the headline multiplier. Monthly payment is calculated using the standard annuity formula: M = P x [r(1+r)^n] / [(1+r)^n - 1], applied at both the actual rate and the stress rate.
Inputs: Annual income: GBP 50,000, Partner income: GBP 0, Monthly expenses: GBP 0, Deposit: GBP 20,000, Interest rate: 5.5%, Term: 25 years
Inputs: Annual income: GBP 50,000, Partner income: GBP 30,000, Monthly expenses: GBP 600, Deposit: GBP 40,000, Interest rate: 5.5%, Term: 30 years
This calculator uses the standard 4.5x income multiple and a 3% stress test buffer, which reflects general UK lending practice. In reality, individual lenders apply their own criteria. Some may use different multiples, cap affordability ratios at different levels, or apply additional criteria based on credit score, employment type, or property location. Self-employed applicants typically need 2-3 years of accounts. Lenders may use the average of the last two years or the lower figure. This calculator does not differentiate between employment types. The calculator does not account for stamp duty, solicitor fees, survey costs, or arrangement fees, which all add to the total cost of buying a property. Use it alongside the stamp duty calculator for a fuller picture of your upfront costs.