How much can I borrow with a mortgage?

If you’re planning to buy a home, working out how much you could borrow with a mortgage is one of the first steps. While you might have your own budget in mind, lenders use their own affordability assessments, which means the amount you’re offered may be different from what you expect.

This guide explains how lenders decide how much to lend, what factors influence their decision, and why two borrowers with similar incomes might be offered very different amounts.

Try our Mortgage Calculator

How many times your salary can you borrow with a mortgage?

Your income is the starting point for most mortgage calculations. In many cases, lenders cap borrowing at around 4.5 times your annual income, although this is not guaranteed and can be lower or higher depending on your circumstances. Following changes by the watchdog in 2025, more lenders are now offering mortgages between 5.5 and 6 times income. Though certain criteria needs to be met before they’re offered these higher than usual borrowing amounts (for example, a first time buyer might need to meet minimum income requirements to be eligible for a higher borrowing amount.

You should also consider whether stretching yourself to the limits of your borrowing power makes sense for your circumstances in the long term.

It’s worth noting that income multiples are only one part of the picture. Lenders also look closely at what you spend each month and how affordable repayments would be if interest rates were to rise. Read more here about credit scores and how lenders use them when looking at mortgage affordability.

How lenders assess how much you can afford to repay

Lenders are required to carry out affordability checks to make sure your mortgage repayments are sustainable. These checks are designed to protect borrowers and are shaped by regulatory standards in the UK.

They will typically look at:

• Your income after tax
• Your regular household spending
• Any existing credit commitments
• How much would be left over each month after mortgage payments

The aim is to understand whether you could continue to afford your mortgage even if your circumstances change.

How a lender’s affordability assessment works

Affordability assessments go beyond simple income multiples. Lenders build a detailed picture of your finances, often using information from bank statements and credit reports.

They may assess:

• Essential spending such as utilities, food and council tax
• Financial commitments like loans, car finance and credit cards
• Lifestyle costs that appear consistently in your spending

Even small regular payments can affect how much you can borrow, as they reduce the amount of income available for mortgage repayments.

Lenders will consider your household living costs  

Lenders consider the day-to-day costs of running your home, as well as your lifestyle costs.  

Most lenders use ‘modelled data’ to determine most of your day-to-day expenditure. This generally comes from data sources such as the Office of National Statistics (ONS) and the Consumer Price Index (CPI). This is a common measure of inflation, which tracks the price change over time for a basket of goods and services.  

The ‘CPI market basket’ is sourced from expenditure information provided by families and individuals of what they’ve purchased. Lenders will also look at inflationary pressures on your expenditure and will take this into account.  

This ‘basket’ is then used to estimate your living costs, and the cost of running your household. This can include things like mobile phone and broadband bills, TV subscriptions and day-to-day social activities.    

Perhaps the most important factor in determining your household cost is the number of people living in your house. Because this takes into account day-to-day living costs, a home with two people will of course cost less than a home with four people living in it. 

How a stressed rate is applied to a mortgage application

As part of the affordability process, lenders usually apply a stressed interest rate. This means they calculate whether you could still afford repayments if interest rates were higher than the deal you’re applying for.

This helps ensure that borrowers are not overstretched and can manage future increases in mortgage costs. A higher stressed rate can reduce the amount a lender is willing to offer, even if your current repayments would be lower.

Here’s an example to help demonstrate how a mortgage stress test could work in practice. 

Say that you and your partner are applying for a mortgage of £210,000 over a 25-year term, and you work out that the income you could put towards your mortgage is £1,500 a month. You check the latest rates and you’ve worked out that you can comfortably afford the 5.5% fixed rate which comes in at £1,290 payment a month. 

This is the stage that you might find frustrating, as if you apply for a Mortgage in Principle on these terms, you could find that a lender won’t approve the amount you have worked out that you can afford. That’s because the lender will assess your affordability using the stressed rate.   

So, while you’ve done your sums against an interest rate of 5.5%, the lender will actually check to see if you can afford a monthly payment when rates are about 8%, meaning that the minimum amount of income you need to put towards your mortgage is just above £1,600 a month. Because this would exceed your available monthly income of £1,500, the lender is likely to say you need to change the amount you’re asking to borrow, or to consider extending your mortgage term.

This is so they can be sure that you’ll be able to afford to make the repayments with the stressed rate applied. Take a look at the example of how a stressed rate might be applied below.

How a stressed rate is applied by lenders to determine how much you can borrow 

This example is based on a mortgage loan of £210,000 over 25-years at 5.5% interest 

Disposable household income	£1,500
Monthly mortgage repayment (5.5% interest)	£1,290
Stressed mortgage payment (8%)	£1,621
Stressed mortgage payment at 8% if mortgage term extends to 34 years	£1,500
Stressed mortgage payment at 8% if amount borrowed reduces to £194,000	£1,497

MORTGAGE GUIDES

What are mortgage terms and how do they work?

What if you’re self‑employed or earn variable income?

If your income varies due to bonuses, commission or self‑employment, lenders will usually take a more cautious approach.

Many lenders:

• Average variable income over two or more years
• Only count a portion of bonuses or commission
• Ask for additional evidence, such as tax returns or accounts

If you’re a freelancer, self-employed, or work ad-hoc hours, such as a zero hours contract, lenders will usually look at an average of your income over a period of time. There is a possibility that the amount you’re able to borrow could be lower than someone with the same headline salary but more predictable income. These policies aren’t consistent between different lenders, so if you have complex or uncertain income, it’s a good idea to speak to a mortgage broker who can help to find the best lender for you. 

Many lenders will be happy to offer mortgages to self-employed people, but there could be more checks and documentation required to prove your affordability.

Learn more about the process of getting a mortgage when you’re self-employed.

What if your mortgage term goes into retirement?

If your mortgage term extends beyond your planned retirement age, lenders will want to understand how you’ll afford repayments later on.

They may ask about:

• Pension income
• Other investments or savings
• Plans to reduce the mortgage balance before retiring

Clear evidence of retirement income can help reassure lenders, but borrowing may still be limited if future income is expected to fall.

How lenders work out how much they will loan to you

Bringing all of this together, lenders combine income, outgoings, credit commitments and stress testing to decide how much to lend.

This table helps illustrate how different factors can influence borrowing amounts, and why two applications can produce very different results.

Working out how much income you could put towards a mortgage

Income and expenditure	Example
Example: Monthly Household Income (after tax)	£3,600
Credit Commitments	-£800
Basic Living Costs	-£900
Other Expenditure	-£400
Income you could put towards a mortgage	£1,500

Our mortgage expert Matt Smith says: “There can sometimes be a difference between the mortgage repayments you’d be prepared to pay, compared to the stress-tested amount that the lender uses to determine affordability.“ 

“Mortgage affordability assessments are detailed, and can be complicated, so by taking people through each stage of the process, hopefully this will help those saving up for a deposit on their first home, or moving to their next home, to get a better understanding of what they can do to get the mortgage they want,” he adds.

 

How a Mortgage in Principle can help

A Mortgage in Principle gives you an early indication of how much a lender might be willing to offer, based on your individual circumstances.

It can:

• Help you understand your realistic budget
• Make you a more credible buyer when viewing properties
• Highlight potential issues before a full application

While it’s not a guarantee, it can provide clarity and confidence at an early stage of your home‑buying journey. Read more about the process of getting a Mortgage in Principle here.

FAQs

• Why is the amount I can borrow different from what I expected?

  Lenders use detailed affordability checks rather than relying only on income multiples. Regular outgoings, existing credit commitments and stress testing can all reduce the amount you’re offered compared with an initial estimate.

• Can I increase how much I can borrow?

  There are some steps that may improve how much a lender is willing to offer, depending on your circumstances. Reducing existing debts, applying jointly, or choosing a longer mortgage term can improve affordability, which may increase the amount you can borrow.

• Does my deposit affect how much I can borrow?

  Your deposit does not usually change the income multiple a lender applies. However, a larger deposit can unlock lower interest rates, which may improve affordability and support a higher borrowing amount, in some cases.

• Will having children affect my mortgage affordability?

  Lenders usually factor childcare costs and other dependant‑related expenses into affordability checks. These regular outgoings can reduce the income available for mortgage repayments and may affect how much you can borrow.

• Can my credit history reduce how much I can borrow?

  Your credit history helps lenders assess risk rather than directly setting a borrowing limit. Missed payments, defaults or high levels of existing credit can reduce affordability or limit the lenders willing to offer you a mortgage.

• Is the maximum I can borrow always what I should borrow?

  The maximum amount reflects what a lender believes you could afford, not necessarily what will feel comfortable. Some buyers choose to borrow less to allow for changes in living costs, interest rates or future plans.

• Is using a mortgage calculator enough to know my budget?

  Mortgage calculators can give a useful starting point, but they are only estimates. A Mortgage in Principle provides a more personalised view based on a lender’s criteria and your financial details.

Please note: Rightmove is not authorised to give financial advice; the information and opinions provided in these articles are not intended to be financial advice and should not be relied upon when making financial decisions. Please seek advice from a regulated mortgage adviser.