About Percentage Calculator

What this site is for

Percentage Calculator provides interactive calculators and clear explanations for the most common percentage problems people encounter in everyday life. The tools cover calculating a percentage of a number, expressing a part as a percentage of a whole, measuring percentage change, working backwards from a final value, and applying percentage calculations to prices through discount, VAT, and sales tax tools.

Every calculator runs in the browser so results appear immediately as you type. Each result is accompanied by the formula used, which means you can see exactly how the answer was reached and apply the same method with pen and paper if needed.

The site is entirely free to use. There is no account to create, no subscription required, and no personal data collected through the calculators.

Editorial approach and content accuracy

All explanatory content on this site is written to be accurate, clear, and useful. Formulas are presented with their correct mathematical form, and examples are checked to produce the stated results. Where a formula has important caveats — such as the undefined result when the baseline is zero, or the difference between percentage change and percentage difference — those caveats are explained rather than glossed over.

Content is written for a general audience and avoids unnecessary jargon. Technical terms are introduced alongside plain-language descriptions so that readers with varying levels of maths confidence can follow along.

If you notice an error in a formula, an incorrect example result, or any other content issue, the contact page explains how to report it.

Who the site is intended for

The site is for anyone who needs to calculate percentages: students converting test marks, shoppers checking sale prices, employees verifying a pay rise, small business owners tracking revenue changes, or professionals who need a quick check of a VAT or tax calculation.

No maths background beyond basic arithmetic is assumed. The explanations assume you know what multiplication and division are, but they do not assume familiarity with algebra or financial terminology.

Limitations and responsible use

The calculators perform the arithmetic correctly for the inputs provided. They do not account for jurisdiction-specific rules, individual circumstances, or factors beyond the numbers entered. In particular:

Tax and VAT calculations show the arithmetic result of applying a given rate to a given amount. Actual tax liabilities depend on a wide range of legal and personal factors that these tools cannot assess. The results should not be used as the sole basis for filing tax returns or making legal or financial decisions.

Financial calculations such as salary changes or budget proportions are illustrative. They do not account for tax deductions, national insurance, pension contributions, or other factors that affect real take-home pay or financial outcomes. For decisions with significant financial consequences, consult a qualified professional.

Scientific and measurement calculations are suitable for general estimation. For calculations that inform safety, compliance, or engineering decisions, use verified specialist tools and professional judgement.

The site is provided as an educational resource. While every effort is made to ensure accuracy, results should be independently verified for high-stakes purposes.