Percentage Calculator

Seven calculation modes covering every common percentage problem. Live answers, visual breakdown, copy or save your work.

What is A% of B?

%

Example: 25% of 80 is 20.

A is what % of B?

Example: 20 is 25% of 80.

From A to B, what is the % change?

Example: 100 to 150 is a 50% increase.

Increase A by B%

%

Example: 100 plus 15% is 115.

Decrease A by B%

%

Example: 100 minus 25% is 75.

If A is the result of a B% , what was the original?

%

Example: 80 after a 20% discount means original was 100.

% difference between A and B

Direction-free comparison: difference over the average of magnitudes.

Result
. . .
Enter values to calculate

How to use

  1. Pick the calculation mode at the top.
  2. Enter the two values. The answer updates as you type.
  3. Use Copy to grab the result, or Save to keep a running history.
  4. The visual on the right adjusts proportionally so you can see the relationship at a glance.

Formulas used

  • % of: result = (A / 100) x B
  • X is what % of Y: result = (A / B) x 100
  • % change: result = ((B - A) / |A|) x 100
  • Add %: result = A x (1 + B/100)
  • Subtract %: result = A x (1 - B/100)
  • Reverse %: result = A / (1 +/- B/100)
  • % difference: result = |A - B| / ((|A| + |B|) / 2) x 100

Frequently asked questions

What percentage problems can I solve here?

Three of the most common: What is X% of Y, X is what percent of Y, and percent change from X to Y. Each one has its own tab with clear input labels.

How is percent change calculated?

Percent change equals (new value - old value) / old value × 100. A positive result is an increase; a negative result is a decrease.

How do I add or subtract a percentage from a number?

Add: multiply by 1 + p/100. Subtract: multiply by 1 - p/100. The calculator does this automatically on the percent-change tab when given a base and percentage.

Are the formulas explained?

Yes. Each tab shows the formula it uses below the inputs so you can double-check the result against your own working.

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