Percentage Calculator
Use this percentage calculator to work out X% of Y, percentage change (old → new), or what percent A is of B. Useful for discounts, growth, and quick comparisons.
Tip: “What percent is A of B?” is calculated as (A ÷ B) × 100.
Pick a calculation type, enter values, then calculate.
How the Percentage Calculator works
This calculator covers three common percentage tasks in one place. Use "Find X% of Y" to work out a percentage of any number — for example, to calculate a tip, a commission, or a percentage of a salary. Use "Percentage change" to find how much a value has grown or fallen between two figures, which is useful for comparing prices, investment returns, or year-on-year changes. Use "What percent is A of B?" to express one number as a share of another.
Percentages are the backbone of UK personal finance. Your income tax is calculated as a percentage of your earnings — the basic rate is 20%, the higher rate 40%, and the additional rate 45%. National Insurance contributions are also percentage-based. Mortgage interest rates, credit card APRs, and savings account AERs are all expressed as annual percentages, making it essential to understand how to interpret and compare them.
A common source of confusion is the difference between percentage points and percentages. If an interest rate rises from 2% to 3%, it has increased by 1 percentage point but by 50% relative to the original rate. This distinction matters particularly when comparing financial products or interpreting economic statistics.
Frequently asked questions
What is a percentage?
A percentage is a way of expressing a number as a fraction of 100. The word comes from the Latin 'per centum', meaning 'by the hundred'. So 25% means 25 out of every 100, or one quarter. Percentages are used universally in finance, statistics, and everyday life to describe proportions, rates, and changes in a way that is easy to compare across different scales.
How do I calculate a percentage of a number?
To find X% of Y, divide X by 100 and multiply the result by Y. For example, 15% of £200 is (15 ÷ 100) × 200 = 0.15 × 200 = £30. You can also move the decimal point two places to the left to convert the percentage to a decimal, then multiply: 15% becomes 0.15, and 0.15 × 200 = 30.
How do I find what percentage one number is of another?
To find what percentage A is of B, divide A by B and multiply by 100. For example, to find what percentage 30 is of 200: (30 ÷ 200) × 100 = 15%. This is useful for calculating what share of a total a particular figure represents — for instance, what percentage of your monthly income goes on rent.
What are percentages used for in everyday finance?
Percentages appear throughout personal finance in the UK. Interest rates on savings accounts and mortgages are expressed as percentages (APR or AER). Income tax and National Insurance are calculated as percentages of earnings. VAT is charged at 20% on most goods and services. Discounts and sale prices are quoted as percentage reductions. Pension contribution rates are percentages of salary. Understanding how to work with percentages is therefore a foundational skill for managing your finances.