Percentage Calculator
How to Use
📖 Tool Introduction
Percentage Calculator is a completely free, instant-use online tool built around the three percentage situations you meet most often in everyday life: finding a part of a number, expressing one number as a percentage of another, and measuring the increase or decrease between two values. Whether you need to work out the discounted price of an item, verify how much commission a deal earns you, or analyse month-on-month and year-on-year changes in a business report, you simply enter two values and pick a mode — the answer appears immediately, with no formula to remember. All computation happens locally in your browser, so your figures are never uploaded to any server and your privacy is fully protected. The interface is available in Simplified Chinese, Traditional Chinese and English, automatically follows the website theme colour and corner-radius style, and works smoothly on both desktop and mobile devices. No registration and no installation are required — just open it and start calculating. It is a high-frequency practical companion for students, accountants, operations staff and everyday shoppers alike. The tool remembers nothing about you: there is no account, no tracking and no cookie involved, so sensitive figures such as salaries, prices and business data can be processed with total peace of mind. When the same calculation needs to be repeated often, the built-in example button and the one-click clear workflow keep the whole routine well under ten seconds, which makes it a genuinely handy desk-side utility rather than a one-off gadget.
✨ Key Features
- Part-of mode: instantly computes what B percent of A equals, ideal for discounts, commissions and tax rates
- Percentage mode: shows what percentage A is of B, perfect for shares, achievement rates and completion statistics
- Change mode: computes how many percent B has increased or decreased relative to A, designed for period-over-period analysis
- Transparent results: every result is accompanied by the formula used, so you can double-check the maths and learn from each step
- One-click copy and download: the result text can be copied to the clipboard or saved as a file for archiving and sharing
- Built-in examples: the example button loads a realistic dataset so you can experience all three modes within seconds
📝 How to Use
- Choose the calculation mode you need from the dropdown list
- Enter the base value in the field labelled Value A
- Enter the second figure in the field labelled Value B
- Click the Calculate button and read the result card, which shows both the answer and the formula behind it
- To try another set of figures, click the Clear button and enter new values
⚠️ Notes
- Valid numbers only: both fields must contain valid numbers; empty or malformed input triggers a friendly warning
- Division by zero: in Percentage and Change modes a zero denominator makes the result meaningless, and the tool will tell you clearly instead of showing nonsense
- Decimal precision: results keep up to four decimal places with trailing zeros removed, which comfortably covers everyday accuracy needs
- Fully local: every calculation runs inside your browser with no network request at all, so nothing ever leaves your device
- Negative values: the Change mode accepts negative inputs, so loss and decline scenarios can be calculated just as easily