CasviaStart with two limits: lender capacity and your own budget
When people ask “how much mortgage can I afford?”, they often mean two different things. The first is how much a lender may be willing to lend. The second is how much monthly payment you can carry without making the rest of your budget fragile.
Those numbers are not always the same. MoneyHelper says lenders use your income and outgoings to assess affordability and typically cap borrowing at around 4.5 times annual income, but that figure is not guaranteed. Your debts, regular spending, employment, deposit and the lender's own criteria can all reduce the amount available.
Source: MoneyHelper — Mortgage affordability calculator.
Step 1: estimate the income-based ceiling
As a rough screening tool, multiply your gross annual household income by a conservative income multiple. Do not treat the result as an approval.
| Household income | 4.0× income | 4.5× income |
|---|---|---|
| £40,000 | £160,000 | £180,000 |
| £60,000 | £240,000 | £270,000 |
| £70,000 | £280,000 | £315,000 |
| £90,000 | £360,000 | £405,000 |
| £120,000 | £480,000 | £540,000 |
This gives you a range to investigate, not a target to borrow. A household earning £70,000 might start by testing loans around £280,000 to £315,000, then reduce that range if the monthly payment leaves too little room for other commitments.
Step 2: subtract the costs your lender will also see
Mortgage affordability is more detailed than a salary multiple. MoneyHelper says lenders consider household bills, living costs and debts such as loans and credit cards. The FCA's mortgage rules also require lenders to take income, committed expenditure, essential spending and future interest rates into account when assessing affordability.
- credit-card and personal-loan payments;
- car finance and other committed credit;
- childcare and other recurring family costs;
- Council Tax, utilities, insurance and essential living costs;
- pension deductions and other regular commitments;
- income stability, including variable or self-employed income.
Sources: MoneyHelper — How to apply for a mortgage; FCA Mortgage Conduct of Business rules.
Step 3: turn the loan into a monthly payment
A borrowing limit only becomes meaningful when you convert it into a repayment. Take a £315,000 repayment mortgage over 30 years:
| Illustrative rate | Approx. monthly payment |
|---|---|
| 4% | £1,504 |
| 5% | £1,691 |
| 6% | £1,889 |
| 7% | £2,096 |
Illustrative repayment calculations only; no fees, insurance or other housing costs included.
This is why affordability can change quickly even if your salary does not. On the same £315,000 loan, the difference between 4% and 7% is roughly £592 a month.
Step 4: add the deposit and check your LTV
Your purchase budget is roughly mortgage + deposit. A larger deposit reduces how much you need to borrow and lowers your loan-to-value (LTV).
For example, a £350,000 home with a £35,000 deposit requires a £315,000 mortgage, which is 90% LTV. The same home with a £70,000 deposit requires a £280,000 mortgage, or 80% LTV.
Lower LTV does not guarantee approval or a particular rate, but it reduces the loan size and can improve the range of mortgage products available. See our UK mortgage deposit guide for common deposit bands.
Worked example: £70,000 household income
Suppose a household earns £70,000 gross a year and has a £35,000 deposit.
- Income screen: 4.5× income gives a rough upper figure of £315,000.
- Purchase price: £315,000 mortgage + £35,000 deposit = £350,000 before purchase costs.
- LTV: £315,000 ÷ £350,000 = 90%.
- Repayment check: at an illustrative 5% over 30 years, the mortgage payment is about £1,691 a month.
- Budget check: add Council Tax, insurance, utilities, maintenance, service charges if applicable, transport, childcare, debt payments and normal living costs.
If £1,691 leaves the household with too little monthly headroom, the affordable mortgage is lower even if a lender's initial income multiple points to £315,000.
Stress-test the payment before you shop for homes
MoneyHelper notes that lenders consider whether repayments remain manageable if rates rise. You can apply the same idea yourself: test the mortgage at a rate one or two percentage points above the deal you are considering, then ask whether the rest of your budget still works.
A useful personal stress test is to check whether you could still cover the mortgage after one of these events:
- a temporary drop in household income;
- higher childcare or commuting costs;
- a major home repair;
- a mortgage reset at a higher rate;
- another debt payment appearing in the budget.
Do not spend your entire deposit on the deposit
Buying a home involves more than the mortgage deposit. Depending on the purchase, you may also need cash for conveyancing, surveys, mortgage fees, moving costs, repairs and property taxes. Keeping a post-completion emergency buffer can be more valuable than using every last pound to push the LTV down by a small amount.
Use the Stamp Duty calculator for England and Northern Ireland, or the separate Scotland and Wales calculators if you are buying there.
What lenders can afford to offer is not what you must borrow
A mortgage agreement in principle can be useful for planning, but the maximum figure is still a ceiling. Your own safe number may be lower. MoneyHelper says there is no single percentage of income that every household should spend on a mortgage; affordability depends on the rest of your circumstances.
A strong home-buying budget leaves room for normal life, not just the mortgage payment. If the plan only works when nothing goes wrong, the property may be too expensive for your current finances.
Frequently asked questions
How much can I borrow on a £50,000 salary?
A rough 4.0× to 4.5× income screen gives £200,000 to £225,000, but a lender may offer less or more depending on outgoings, debts, deposit, income stability and its own criteria.
How much can a couple borrow?
Lenders can consider eligible income from both applicants, then assess the household's combined expenditure and debts. Two incomes do not automatically double affordability because the household may also have higher committed costs.
Does a bigger deposit help mortgage affordability?
Yes. A bigger deposit reduces the mortgage required and lowers LTV. That reduces the monthly payment at the same rate and term, and may improve the products available.
Should I borrow the maximum the bank offers?
Not automatically. The bank's maximum is an eligibility decision. Your own budget should also leave room for rate changes, home maintenance, insurance, household costs and emergencies.
Sources
- MoneyHelper — Mortgage affordability calculator
- MoneyHelper — How to apply for a mortgage
- MoneyHelper — How much should I spend on a mortgage?
- Financial Conduct Authority — Mortgage Conduct of Business sourcebook
Educational guide only — not mortgage advice. Lender criteria, rates and affordability rules vary. Check current lender terms and, if needed, speak to a regulated mortgage adviser.