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Mortgage affordability calculator

Explore a user-controlled borrowing range and monthly-payment stress scenarios. This is not a lender affordability assessment, approval or eligibility check.

Your scenario

Build a transparent range. This does not reproduce any lender’s assessment.

Gross income before tax.

Enter £0 for one applicant.

Bonus, overtime or commission scenario.

A user-controlled assumption.

Added to the borrowing range.

Loans, maintenance and other fixed commitments.

Whole years from 1 to 50.

Used only for monthly-payment scenarios.

Income-multiple range

These assumptions are editable and are not lender promises.

Lower end of the scenario.

Upper end of the scenario.

Illustrative borrowing range

£290,000.00–£326,250.00

not an offer, approval or eligibility result

Purchase-price range
£340,000.00–£376,250.00
Assessable income
£72,500.00
Stressed payments
£1,929.38–£2,170.55
Payments + commitments
£2,529.38–£2,770.55

Important: This is an illustrative range, not a lender decision, agreement in principle or indication of eligibility.

Scenario detail

MeasureLowerUpper
Borrowing£290,000.00£326,250.00
Purchase price£340,000.00£376,250.00
Deposit / price LTV85.3%86.7%
Stressed monthly payment£1,929.38£2,170.55

Calculation mortgage-affordability@1.0.0. Lenders assess circumstances and product rules differently and may lend less or nothing.

Assumptions used

  • The lower and upper scenarios use 4× and 4.5× assessable annual income.
  • 50% of entered variable income is included.
  • Monthly repayments are illustrated at 7% over 30 years.
  • Committed outgoings are shown beside mortgage payments and are not converted into a proprietary loan deduction.
  • Taxes, insurance, maintenance, service charges and mortgage fees are excluded.

How the scenarios work

The calculator first adds primary income, second income and the selected percentage of variable income. It multiplies that assessable income by the editable lower and upper multiples; it does not claim those multiples are available from a lender.

assessable income = fixed income + included variable income

illustrative borrowing = assessable income × chosen multiple

illustrative purchase price = borrowing + deposit

Monthly repayments are then modelled at the entered stress rate and term. Entered commitments are added beside that payment rather than being converted into a hidden or proprietary-looking loan deduction.

Worked example

With £70,000 of fixed income, £5,000 variable income included at 50%, a £50,000 deposit and a 4×–4.5× range, the illustration produces borrowing of £290,000.00–£326,250.00 and purchase prices of £340,000.00–£376,250.00.

At the example 7% stress rate over 30 years, modelled monthly mortgage payments are £1,929.38–£2,170.55. This is generated by mortgage-affordability@1.0.0.

What this result does not tell you

A lender can assess income, expenditure, credit history, age, dependants, property, product and regulatory rules differently. It may lend less than this illustration or nothing.

  • Income multiples are scenario controls, not lender criteria.
  • Gross income is not take-home pay.
  • Tax, insurance, maintenance, service charges and mortgage fees are excluded.
  • The tool does not assess creditworthiness or recommend a borrowing amount.

Your home may be repossessed if you do not keep up repayments on your mortgage.

Sources and change log

The tool contains no lender model, product ranking or rate feed. Its generic-information boundary follows FCA MCOB 5.4 and FCA PERG 4.6.

20 August 2026: initial transparent multiple-range and stressed-payment calculator added.

Questions people ask

Is this how much I can borrow?

No. It is a range created from assumptions you control. Only a lender can assess an application and it may offer less or nothing.

Why are committed outgoings shown separately?

There is no single public formula that truthfully converts every monthly commitment into a maximum-loan deduction across lenders.