ToolsDiary
Utility tool

Percentage Calculator

Calculate percentages, percentage change, percentage difference and increases or decreases.

Use the tool

Privacy-first: this tool runs in your browser. Your input is not sent to ToolsDiary unless the page explicitly says otherwise.

What is X% of Y?

Example: 20% of 150 = 30.

What this tool does

Solve common percentage calculations in one place. Find a percentage of a number, determine what percentage one value is of another, calculate percentage increase or decrease, compare two values with percentage difference, or add and subtract a percentage from a number.

Percentages describe a value relative to 100, but different percentage questions use different formulas. Percentage change compares a new value with an original value, while percentage difference compares two values without treating either one as the starting point. This calculator keeps those operations separate and shows the formula used so the result is easier to understand.

Useful for

  • Calculate discounts, taxes, tips, commissions and markups.
  • Measure percentage increases or decreases between two values.
  • Find what share one number represents of another.
  • Compare two values using percentage difference.

How to use it

  1. Choose the percentage calculation you need.
  2. Enter the required numbers in the labeled fields.
  3. Select Calculate to see the result and formula.
  4. Use Reset or choose another calculation for a new problem.

Practical tips

  • For percentage change, the original value is the reference value and cannot be zero.
  • Percentage difference is symmetric: swapping the two values gives the same percentage difference.
  • A 20% increase followed by a 20% decrease does not return to the original number because the second percentage uses a different base.
  • The calculator runs locally in your browser and does not send entered numbers to ToolsDiary.

Frequently asked questions

How do I calculate 20% of 150?

Use the “What is X% of Y?” calculator. Enter 20 and 150. The result is 30.

What is the difference between percentage change and percentage difference?

Percentage change measures movement from an original value to a new value. Percentage difference compares two values relative to their average and does not require a starting value.

Can percentage change be more than 100%?

Yes. If the increase is larger than the original value, the percentage increase can exceed 100%.

Why can’t percentage change start from zero?

The standard percentage-change formula divides by the original value. Division by zero is undefined, so a normal percentage change from zero cannot be calculated with that formula.

Are my numbers saved?

No. Calculations run in your browser and the values are not sent to ToolsDiary.