Mortgage Affordability Calculator
Buying a home usually starts with one question: how much might I be able to borrow? Our mortgage affordability calculator gives an indicative estimate rather than a single definitive figure — a conservative range, a standard range, and a higher range for stronger applications — based on the income, employment type, existing debts, deposit and household circumstances you enter. It also applies an interest rate stress test broadly in line with the approach UK regulation requires lenders to take, so the figures shown are intended as a planning guide for early-stage house-hunting, not a substitute for a formal assessment from a lender or broker.
How Much Can I Borrow?
Estimate your maximum mortgage based on income, outgoings and deposit using standard UK lender income multiples.
How Affordability Estimates Are Typically Assessed
This is an indicative estimate, not a lending decision. It is not financial advice, not a Mortgage Agreement in Principle, and not a guarantee of what any individual lender would offer. Every lender applies its own affordability model, and the figures below can only approximate common, publicly available industry criteria.
UK mortgage lenders do not rely on a single fixed income multiple. The Financial Conduct Authority (FCA) requires lenders to carry out an affordability assessment, and while individual affordability models vary considerably between lenders, they commonly combine an income multiple with several further adjustments:
- Income multiple — how many times gross annual income a lender may be willing to advance, which typically varies by employment type and number of applicants.
- Existing debt — monthly repayments on credit cards, loans, car finance and other borrowing generally reduce the amount a lender is willing to advance.
- Dependants — children and other dependants reduce disposable income, which lenders commonly factor into their assessment.
- Stress testing — lenders are required to check that a borrower could still meet monthly payments if interest rates rose, typically by testing affordability at a higher rate than the one actually being offered.
Our calculator applies a simplified version of this general approach so the estimate reflects widely-used UK affordability principles. It does not replicate any specific lender’s underwriting model, and different lenders assessing the same applicant may reasonably reach different conclusions.
The Bank of England places a market-wide constraint on lenders: no more than 15% of a lender’s new mortgage lending can be issued above 4.5 times income. This is one reason two lenders may offer noticeably different amounts to the same applicant — some may have more capacity remaining within that limit than others at any given time.
Assumptions Used In This Estimate
- Income multiples of 4.0–5.0x for employed applicants and 3.75–4.75x for self-employed applicants, reflecting figures commonly published across the UK mortgage market.
- Debt reduction calculated at roughly £10 less borrowing for every £1 of monthly committed debt.
- A flat reduction of £10,000 per dependant, as an approximation of the extra living-cost allowance many lenders apply.
- A stress-tested rate of typical rate + 3 percentage points, checked against 45% of estimated net monthly income.
- Net monthly income approximated at 75% of gross monthly income, which will not exactly match every individual’s actual deductions.
Changing any of these assumptions would change the result. Actual lender criteria, stress rates and income multiples vary and change over time, so figures here should be treated as broadly indicative rather than precise.
The Calculation Method
The estimate is produced in two stages: an income-based loan figure, followed by a stress test to check it against estimated affordability.
Stage 1 — Income-based loan estimate:
| Employment type | Conservative | Standard | Higher end |
|---|---|---|---|
| Employed (PAYE) | 4.0x | 4.5x | Up to 5.0x* |
| Self-employed / contractor | 3.75x | 4.25x | 4.75x |
*Sole applicant, illustrative of a stronger credit profile and larger deposit — not a guaranteed outcome.
Stage 2 — Stress test:
The monthly payment is estimated using a standard mortgage amortisation calculation. If the stress-tested payment exceeds 45% of estimated net income, the standard figure is shown as less likely to be considered affordable on the assumptions used, which may indicate that a larger deposit, longer term, or lower loan amount would need to be considered.
Worked Examples
These are illustrative only, using round figures to show how the calculation works — they are not case studies or real applications.
Example 1 — Single applicant, employed, no dependants. On an income of £45,000 with no other debt and a £30,000 deposit: £45,000 × 4.5 = £202,500 standard estimate, giving an indicative maximum property price around £232,500.
Example 2 — Joint application, employed, one dependant, some debt. On a combined income of £70,000, a £250/month car finance repayment and one dependant: 4.5 × £70,000 = £315,000, less £30,000 debt reduction (£250 × 10 × 12) and £10,000 dependant reduction, giving an indicative standard estimate around £275,000.
Example 3 — Self-employed applicant. On a self-employed income of £60,000 with no dependants or existing debt: the lower standard multiple of 4.25x (rather than 4.5x) gives an indicative estimate around £255,000.
Frequently Asked Questions
How much might I be able to borrow based on my salary?
As a general guide, UK lenders commonly advertise income multiples in the range of 4 to 4.5 times gross annual income, with some offering up to around 5 times for employed applicants with a stronger credit profile and larger deposit. Self-employed applicants typically see multiples around 0.25x lower at each tier. Individual outcomes depend on the specific lender’s own criteria.
Is a partner’s income included?
On a joint mortgage application, lenders typically combine both incomes before applying the income multiple, which is why this calculator has a separate field for a partner’s income.
Why do self-employed applicants often see lower estimates?
Lenders commonly treat self-employed and contractor income as less predictable than a fixed PAYE salary, which is often reflected in a slightly lower income multiple. Self-employed applicants are typically asked to provide 2–3 years of accounts or tax returns (SA302s) as supporting evidence.
What is typically counted as debt in an affordability assessment?
Credit card balances, personal loans, car finance, student loan repayments and other regular committed monthly outgoings are commonly included. Lenders typically review bank statements covering the preceding 3–6 months as part of this assessment.
What does mortgage stress testing mean?
It refers to a lender checking whether a borrower could still meet monthly payments if interest rates were higher than the rate actually being offered — typically tested at several percentage points above. This is a regulatory requirement rather than a lender preference.
Could first-time buyers see a different estimate?
Some lenders offer enhanced income multiples for first-time buyers in specific circumstances or professions. These vary by lender and are not reflected in the general figures used in this calculator.
Is this the same as a Mortgage Agreement in Principle (AIP)?
No. This is a general planning estimate based on commonly published industry criteria. An Agreement in Principle is a formal, lender-specific outcome based on a credit search and full financial details, and is generally what is required once an offer is being made on a property.
How much deposit is typically required?
UK mortgages commonly require a minimum deposit in the region of 5–10% of the property price, with a deposit of 15% or more often associated with more competitive interest rates. See our Mortgage Deposit Savings Calculator for a separate planning tool.
Does credit history affect this estimate?
This calculator estimates affordability based on income and outgoings only — it does not assess credit history. Missed payments, high credit utilisation or a County Court Judgment are factors individual lenders may separately take into account, which could result in a different outcome than the figures shown here.
Important Information
This calculator is provided for general information and planning purposes only. It does not constitute financial advice, a mortgage recommendation, or a lending decision, and should not be relied upon as such. Figures are indicative estimates based on simplified, publicly available industry criteria and stated assumptions, and will not reflect the specific underwriting model of any individual lender. Actual borrowing amounts depend on a full assessment by a lender or a suitably qualified, FCA-regulated mortgage adviser, who can consider your full circumstances. See our Disclaimer for further information.