Start with the payment you can live with
That keeps the range grounded in monthly reality rather than in a headline borrowing number that may feel uncomfortable once all the other costs arrive.
Affordability Calculator
Mortgage affordability calculator for budget-led borrowing plans
Estimate a borrowing range from the monthly payment you want to keep manageable, your household income and your deposit. Use it to set a property budget before you ask a lender for an Agreement in Principle.
Monthly payment planningIncome reference and deposit contextAgreement in Principle preparation
Income Reference
A common planning cap is around 4.5x annual income
Deposit Range
Many buyers plan around roughly 5% to 10%
AIP Window
A mortgage in principle often lasts 30 to 90 days
On This Page
Planning Tool
Test the payment you want to live with, not just the biggest number on paper
Start with the monthly payment you want to keep realistic. The planner then compares that number with an income reference point around 4.5 times annual income, so you can see both the payment-led and income-led limits before you set a property budget.
Planning inputs
Use the planner to compare two limits: the monthly payment you want to keep comfortable and an income reference point based on around 4.5 times annual income.
£
Use the income figure you expect to evidence to a lender.
£
Leave at £0 for a single application.
£
Deposit is added after the borrowing estimate to show an indicative property budget.
£
Enter the monthly payment you want to test after allowing for bills, credit commitments and living costs.
%
Use a quoted rate if you already have one. Otherwise, test several scenarios.
years
Use the range as a starting point
- Many lenders start with an income multiple around 4.5x, but the final offer can still move once full affordability checks begin.
- If you are self-employed, test with the income figure you can support with tax returns or accounts rather than with turnover or headline revenue.
- This planner does not model credit scoring, lender stress tests, property type restrictions or scheme-specific underwriting.
Planning result
Cautious borrowing figure
£225,000Estimated property budget
£255,000Deposit used
£30,000Resulting LTV
88.24%Deposit as % of budget
11.76%How the figure was built
Budget-based borrowing
£245,563Income reference cap
£225,0004.5x combined income
Monthly payment tested
£1,400.00Payment at cautious figure
£1,282.76Payment at reference cap
£1,282.76Combined income
£50,000Reading the result
The income reference cap is tighter than the borrowing implied by your chosen monthly budget, so the planner uses the 4.5x reference figure. In practice, a lender may still come in lower or higher depending on their own affordability checks.
Deposit reality check
Many buyers plan around a deposit of roughly 5% to 10% of the property price. Use the deposit percentage here as a planning check rather than assuming every lender will offer the same maximum LTV.
How To Read It
How to read the affordability range
The result works best when you treat it as an early planning range. These points show how the borrowing figure is built and what still depends on the lender, the property and your evidence.
The 4.5x income line is a reference point, not a promise
Around 4.5 times annual income is a useful reference line, but it is not a guaranteed offer. The value here is seeing that income-based ceiling alongside the monthly payment range you actually want to keep manageable.
Deposit changes the property budget, not just the mortgage size
A larger deposit can widen the purchase options and improve the loan-to-value position, so the planner keeps deposit context visible instead of treating the mortgage amount in isolation.
A lender still decides the real application
Spending, credit history, deposit evidence, the property, scheme rules and stress testing still shape the decision once you move beyond early planning and into a real application.
Examples
Income and deposit snapshots to frame the property search
These examples show how the income reference point and a deposit can combine into an early property budget. They are not lender offers, stress-tested approvals or scheme-specific outcomes.
| Combined income | 4.5x reference cap | Illustrative property budget with a £30,000 deposit |
|---|---|---|
| £35,000 | £157,500 | £187,500 |
| £50,000 | £225,000 | £255,000 |
| £80,000 | £360,000 | £390,000 |
Next Steps
What to prepare before you turn a planning number into an application
Once the range looks realistic, the next job is to organise the evidence, deposit trail and buying costs that will shape the real application.
Income evidence
Employed applicants usually need payslips and bank statements. Self-employed applicants should usually be ready with tax returns and business accounts for the last two or three years.
Deposit evidence
Make sure the deposit is traceable through bank statements and that any gifted deposit paperwork is ready before full application.
Agreement in Principle
An Agreement in Principle is only an early written estimate and it can involve either a soft or a hard search. Check the lender approach before applying to several lenders at once.
Buying costs outside the mortgage
You still need to budget for legal fees, surveys, removals and other buying costs. That is why the next tool after affordability is usually the fees and stamp duty calculators.
Stamp Duty Calculator
Add current SDLT to the purchase budget instead of treating borrowing capacity as the full picture.
Fees and Costs Calculator
Bring legal fees, surveys and moving costs into the same plan before making an offer.
First-Time Buyer Guide
Read the wider guide if you want the broader deposit, scheme and process context around this planner.
First-Time Buyer Advice
Read the topic hub for the current 2026 rules, scheme status and next-step routing.
Frequently Asked Questions
Does this affordability calculator tell me exactly what a lender will offer?
No. It is an early planning tool. Many affordability estimates start around 4.5 times annual income, but a lender still checks spending, credit history, deposit, stress testing and the property before making a formal decision.
Why does the planner show a 4.5x income reference cap?
Because it is a common starting reference in mortgage affordability guidance. The planner lets you compare that income-based ceiling with the monthly payment budget you actually want to live with.
How much deposit do buyers usually need?
Many buyers plan around a deposit of roughly 5% to 10% of the property price, although a larger deposit can widen the choice of products and improve pricing.
What if I am self-employed?
Be ready with tax returns and business accounts for the last two or three years. The planner does not automatically reduce the borrowing figure for self-employed cases because evidence requirements vary by lender and income pattern.
Does an Agreement in Principle affect my credit file?
It can. Some lenders use a soft search and others use a hard search, so it is worth checking the lender approach before applying to several lenders at once.
How long can a mortgage in principle last?
Often around 30 to 90 days, depending on the lender.