Percentage Calculator

Simple % Calculator Online — calculate percentages, conversions, increases, decreases & changes.

Quick actions
Tap a function, enter values, then Calculate.

What is this tool?

A lightweight, no-friction percentage calculator for common tasks: find X% of Y, what percent one value is of another, increase/decrease by a percent, convert between percent and decimal, and calculate percent change.

  • Find X% of Y — e.g., 15% of 200 = 30.
  • What percent is A of B — e.g., 30 is 15% of 200.
  • Increase/Decrease by % — apply percentage change to a value.
  • Percent ⇄ Decimal — convert formats for programming or finance.
  • Percent change — calculate relative increase/decrease between two values.

Key features

  • Multiple percentage operations in one place
  • Input validation and friendly error messages
  • Copyable, readable output area (textarea)
  • Responsive layout for mobile & desktop
  • SEO-friendly headings and accessible labels

How to use

  1. Select the operation from the dropdown.
  2. Enter numbers in Value A and Value B according to the chosen operation (placeholders guide expected values).
  3. Click Calculate. The result displays in the output area and is easy to copy.
  4. Click Clear to reset inputs and output.

Real-world use cases

  • Quickly compute discounts, markups, and sales tax.
  • Convert percentage points for reports and spreadsheets.
  • Calculate percent change for KPIs and performance reviews.
  • Convert percentages for programming or data input (percent ⇄ decimal).

Benefits

  • Saves time — common percentage calculations in seconds.
  • Reduces human error with built-in validation.
  • Accessible: clear labels, keyboard-friendly controls.
  • Portable: works on mobile and desktop with the same UI.

FAQ

What does “Find X% of Y” mean?

It means multiply Y by X% (for example, 20% of 50 = 0.20 × 50 = 10).

How do I convert a percent to a decimal?

Divide the percent by 100. Example: 25% → 0.25. Use the “Percent → Decimal” operation.

What is percent change?

Percent change = ((new – old) / old) × 100. Positive means increase, negative means decrease.

What if I enter invalid numbers?

The calculator validates inputs and will show clear error messages in the output area. Correct formatting examples: 15, 0.5, -12.3

Is this tool suitable for financial calculations?

Yes for quick checks and small calculations. For legal/financial decisions, use an accountant or financial software for rounding rules, taxes, and regulatory requirements.

Disclaimer: This calculator is provided for convenience and educational purposes only. While we do our best to ensure correctness, results may vary depending on rounding and input accuracy. Do not use this tool as a sole basis for major financial, legal, or medical decisions.

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