Xamia Tools

Percentage Calculator - Solve Everyday Percent Problems

Find a percentage of a number, calculate percent change, and work out increase or decrease. Instant results, no signup, no tracking.

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What is a percentage of a number?

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Formula: (percentage ÷ 100) × number

One number is what percent of another?

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Formula: (part ÷ whole) × 100

Percentage change from one value to another

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Formula: ((new − original) ÷ original) × 100

Find the original number from a percentage

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Formula: part ÷ (percentage ÷ 100)

Four common percentage problems in one place

Percentages appear in discounts, interest rates, tips, test scores, and business reports. This page covers the four calculations people need most often: finding a percentage of a number, finding what percentage one number is of another, measuring the change between two values, and working backwards from a part to the whole. Enter your numbers and each result updates immediately.

How to use the percentage calculator

  1. Choose the right box. Each box solves a different type of problem. The formula is shown below the result.
  2. Enter two values. You can use decimals and negative numbers. Empty fields show a dash until both values are present.
  3. Read the result. Percentage answers include a percent sign. Percentage change also says whether the value increased or decreased.

The results update as you type, so you can compare values quickly without pressing a button.

Tips and examples

  • To find 15% of 200, use the first box: 15 and 200 give 30.
  • If 30 is 25% of a number, the fourth box gives 120.
  • A change from 80 to 100 is a 25% increase, while a change from 100 to 80 is a 20% decrease. The starting value is always the denominator.
  • Percentage change is undefined when the original value is zero, because division by zero has no finite result.

When to use it

Use these calculators to check a discount, compare prices, work out a tip, review a grade, or understand a growth figure. For tax and loan decisions, use the dedicated financial calculators and confirm important numbers with a professional.

Frequently asked questions

How do I calculate a percentage of a number?

Enter the percentage and the number in the first mode. The result updates as you type.

Can it calculate percentage increase or decrease?

Yes. Use the change mode and enter the old and new values.

Can it find the original number from a percentage?

Yes. In the reverse mode, enter the known part and the percentage it represents.

Does it round the result?

Results are displayed with a sensible number of decimal places, and the full value is used in calculations.