What mortgage size can I get?

One of the first questions homebuyers ask is: “How much mortgage can I borrow?” The honest answer is that there isn’t a single figure that applies to everyone. Your maximum borrowing potential depends on how a lender assesses your affordability and risk.

In practice, the mortgage size you’re offered is influenced by factors such as:

• Your income (and how reliable it is)
• Your existing commitments (loans, credit cards, maintenance payments, etc.)
• Your deposit and the resulting loan-to-value (LTV)
• Your credit history
• The property and mortgage structure (term, repayment type)

Because lenders review applications on a case-by-case basis, two people with the same salary can receive different borrowing outcomes.

What determines how much you can borrow?

Mortgage lenders carry out an affordability assessment to decide how much they’re willing to lend to you. While the exact approach varies, most assessments follow a similar pattern: they look at what you earn, what you already pay out each month, and whether you can comfortably afford the new mortgage payments.

A typical affordability assessment will consider:

1) Annual income

Lenders generally assess employment income and may also consider additional income such as overtime, bonuses, commission or other regular payments.

If you’re self-employed, many lenders focus on evidence of income over time (for example, profit levels and consistency), rather than a single year.

2) Financial commitments and monthly outgoings

Your mortgage isn’t assessed in isolation. Lenders also consider your other monthly obligations, including:

• Personal loans
• Credit cards (often using a conservative monthly figure)
• Hire purchase (HP)
• Car finance
• Child maintenance payments
• Any other regular debts

The goal is to ensure that, after accounting for your mortgage repayment, you still have enough income left to cover day-to-day spending.

3) Credit history

A lender will carry out a credit check and review how you’ve managed credit in the past.

Issues such as missed payments, defaults, or certain types of adverse credit history can reduce the amount you can borrow or affect whether a lender is willing to lend.

4) Deposit size and loan-to-value (LTV)

Your deposit directly affects the LTV ratio, which is the percentage of the property price you’re borrowing.

As a general principle, a larger deposit usually means a lower LTV, which can improve the lender’s view of risk.

5) Mortgage term and repayment type

The term you choose affects affordability because it changes the monthly repayment amount.

Similarly, whether you repay principal and interest or structure the mortgage differently can affect how lenders assess the ongoing cost.

Why mortgage calculators can be misleading

Online mortgage calculators are useful for rough planning—for example, estimating monthly payments based on a chosen interest rate.

However, calculators typically don’t reflect the full affordability assessment lenders use. They may ignore important details such as:

• Your existing debts and credit commitments
• How lenders treat irregular income
• Stress-testing assumptions
• The impact of deposit/LTV on borrowing limits
• Credit history considerations

As a result, a calculator might suggest you can borrow more (or less) than a lender would actually offer.

Are your monthly repayments based on your salary?

Your monthly repayment is determined by the mortgage amount, interest rate, and term.

Your salary doesn’t directly set the repayment figure, but it does influence how much you can borrow because lenders use your income to judge affordability.

Most lenders will:

1. Estimate your monthly income
2. Subtract your monthly commitments
3. Apply affordability rules and stress-testing to check you can still afford repayments under more demanding conditions

So, while salary doesn’t “calculate” the repayment amount, it strongly affects the maximum mortgage size you may be offered.

How income multiples fit into the picture

You may hear that lenders lend around a certain number of times your annual income. While income multiples can be a helpful starting point, they are not the full story.

Even if two borrowers have the same salary, the lender’s final decision can differ because affordability also depends on:

• Deposit and LTV
• Other debts and outgoings
• Credit history
• The mortgage term and repayment structure
• The lender’s internal affordability model

In other words, income multiples can indicate a broad range, but they don’t replace an affordability assessment.

Practical examples: what can affect mortgage size

Rather than treating any single number as guaranteed, it’s more useful to understand how changes in your circumstances can move the needle.

If your deposit increases

A higher deposit can reduce LTV, which may improve the lender’s risk position and help you access a larger borrowing amount.

If your monthly outgoings reduce

Paying down debts or reducing credit commitments can improve affordability because more of your income is available to support the mortgage repayment.

If your income is more stable or better evidenced

Lenders may be more comfortable with income that is consistent and well-documented, which can support a stronger affordability assessment.

How to improve your mortgage affordability

If you’re trying to increase the mortgage size you can borrow, the most effective steps are usually the ones that improve affordability from the lender’s perspective.

Consider the mortgage term

A longer term can reduce monthly repayments, which may improve affordability. The trade-off is that you may pay more interest over the life of the mortgage.

Strengthen your income picture

If you have additional income (such as overtime, commission, dividends, or rental income), ensure you can evidence it appropriately.

Reduce existing commitments

Paying down loans and credit cards can help lower monthly outgoings. Even small reductions can matter in affordability calculations.

Avoid new credit before applying

Taking on additional credit shortly before a mortgage application can affect affordability and credit scoring.

Save for a larger deposit

If you’re close to a target LTV, increasing your deposit can make a meaningful difference.

Explore options for joint applications (where relevant)

Some borrowers may be able to apply with a second applicant, depending on the lender’s approach and the household circumstances. This can improve affordability where it’s appropriate and properly structured.

What to do with this information

A realistic way to approach mortgage borrowing is to treat “how much you can borrow” as a range shaped by affordability—not a single number.

Before you commit to a property price, it helps to:

• Review your monthly outgoings and debts
• Consider how your deposit affects LTV
• Think about how your income is evidenced and assessed
• Understand that calculators are only an approximation

Mortgage lenders will ultimately decide the maximum amount based on their affordability assessment and the details of your application.

Related topics

• Getting a mortgage with a new job
• Mortgage affordability for specific professions
• How credit history can affect what you can borrow