Percent of Income Calculator

How it works

Expressing an expense as a percentage of income gives you a standardised way to assess affordability and compare your spending to household budgeting benchmarks. A rent payment of £900 per month means different things depending on whether you earn £1,500 or £4,000 per month.

The formula

Use the same period for both values (both monthly or both annual). The result tells you what share of your income is absorbed by that cost, with the remainder showing what is left.

UK benchmarks

• Rent or mortgage: below 33% of net income is the widely cited affordability threshold
• Pension contribution: 8% minimum (combined employer and employee under auto-enrolment); 15% or more is recommended for a comfortable retirement
• Food and groceries: 10-15% of household income is typical for a UK family
• Council tax: roughly 3-5% of median income depending on band and area

Worked examples

When to use this

• Assessing housing affordability: Before signing a tenancy agreement or taking out a mortgage, check whether the monthly payment exceeds 33% of your take-home pay.
• Reviewing pension contributions: Checking whether your current contribution rate meets the auto-enrolment minimum and whether you are on track for your retirement goals.
• Annual budgeting: Breaking down where your income goes across all categories to identify areas where spending could be reduced.
• Salary negotiation: Calculating what percentage of a new salary would go on your fixed costs to assess whether a job offer at a different location is genuinely better in practice.

Understanding the result

Financial advisers typically recommend that total housing costs (rent or mortgage plus any service charges) do not exceed 30-33% of net income. If you are above this, you may be financially stretched and vulnerable to unexpected costs.

Use gross income (before tax) or net income (after tax) consistently. Net income gives a more accurate picture of actual affordability since you cannot spend gross income. For pension calculations, use gross income as contributions are calculated before tax.

Related concepts

➡ To find what pound amount a percentage of your salary represents, use the percentage of a number calculator to convert any rate into a cash figure. ➡ If you want to see what your gross salary would need to be to achieve a particular take-home, the reverse percentage calculator works backwards from a net figure to the original. ➡ For tracking how your pay has changed over time, use the percentage change calculator to find the size of any salary increase or reduction.

How to do this in Excel

Put the expense in A1 and income in B1. Both must use the same time period.

How to do this without a calculator

Divide the expense by your income, then multiply by 100. For a quick check against the 33% rent threshold: if your rent is a third of your income or more, it is at or above the benchmark. Divide your income by 3 and compare.

Common mistakes

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