Percentage calculator

Solve percentage problems in seconds.

Last updated: January 9, 2026

Built and maintained by Aaron Jegla

Calculate percent of a number, percent change, and markups or discounts without a spreadsheet.

Results are shown as plain numbers so you can apply your own units.

Percentage details

Pick the question you want to answer.

Enter the percent, not the decimal (example: 15).

This is the base number you want a percent of.

For quick discounts, markups, and percentage comparisons.

Not for compounding growth. Try the interest calculator.

How to use this calculator
  1. Pick the calculation type you need.
  2. Enter the values shown for that mode.
  3. Select Calculate to see the results.

Use Reset to return to the default examples.

Summary

Results are based on the selected percentage formula.

Result

0

Percent used

0%

Base value

0

Multiplier

0

Mode: Percent of a number | Formula: (percent / 100) x value

Sources: Mathplanet calculating with percentages, Khan Academy finding percentages example

Assumptions: Percent change uses the starting value as the base. Increase or decrease applies a single percent change to the starting value. Results are rounded to two decimal places.

Disclaimer: Estimates only. Double-check critical values or regulatory calculations.

How this calculator works

Each mode uses a standard percentage formula.

Percent of a number: Result = (percent / 100) x value

What percent is it: Percent = (part / whole) x 100

Percent change: Percent change = (new - old) / old x 100

Increase or decrease: New value = value x (1 +/- percent / 100)

If the starting value is 0, percent change is undefined because it divides by the starting value.

Percentage tips and assumptions

Quick context to help you interpret the results.

Pick the right base

Percent change always uses the starting value as the base.

  • Switching the base flips the percent.
  • Use the original value for growth or decline.

Percent vs percentage points

Percent change compares two numbers. Percentage points compare two percentages.

  • 5% to 6% is +1 percentage point.
  • That same move is a 20% increase.

Discounts and markups

Use Increase or decrease by percent for pricing changes.

  • Decrease for discounts.
  • Increase for markups or tips.

Values over 100%

Percentages can exceed 100% when the part is larger than the whole.

  • This is normal for growth comparisons.
  • Double-check the base value if results surprise you.

Negative results

Negative percentages indicate a decrease or a negative part value.

  • Confirm the sign of your inputs.
  • Use absolute change to see the raw difference.

Rounding

Results are rounded to two decimals for readability.

  • Keep full precision when needed.
  • Small rounding differences are normal.

How to calculate percentages

Percentages compare a part to a whole using a base of 100. Use the mode that matches the question you are trying to answer.

Below are quick, step-by-step examples for each calculator mode.

Example: What is 15% of 200?

  1. Convert 15% to a decimal: 0.15.
  2. Multiply 0.15 x 200 = 30.

Example: 45 is what percent of 180?

  1. Divide 45 by 180 = 0.25.
  2. Convert to a percent: 0.25 x 100 = 25%.

Example: Percent change from 120 to 150

  1. Find the difference: 150 - 120 = 30.
  2. Divide by the start: 30 / 120 = 0.25.
  3. Convert to a percent: 0.25 x 100 = 25% increase.

Example: Decrease 80 by 10%

  1. Convert 10% to a decimal: 0.10.
  2. Multiply 80 x 0.10 = 8.
  3. Subtract: 80 - 8 = 72.

Percentage calculator FAQs

Click a question to expand the answer.

What is the difference between percent change and percent of a number?

Percent of a number finds a portion of a base value. Percent change compares a new value to the starting value to show increase or decrease.

Why is percent change undefined when the starting value is 0?

Percent change divides by the starting value. When the start is 0, the division is undefined, so the calculator asks for a non-zero starting value.

Can a percentage be greater than 100%?

Yes. If the part is larger than the whole, the percent will exceed 100%.

How do I calculate a discount or markup?

Use the Increase or decrease by percent mode. Enter the starting value, the percent, and pick increase for markups or decrease for discounts.

What are percentage points?

Percentage points describe a direct difference between two percentages. For example, a move from 5% to 6% is a 1 percentage point increase.

Does the calculator round results?

Yes. Results are rounded to two decimal places for readability. Use full precision values for critical calculations.

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