Results are arithmetic and rounded to two decimal places. Percentage increase or decrease is always calculated relative to the old value, which is the standard method in most uses.

Three everyday percentage calculations

X% of a number: multiply the number by the percentage and divide by 100. 15% of 200 = 30.
What percent: divide the part by the whole and multiply by 100. 45 out of 50 = 90%.
Percentage change: subtract the old value from the new, divide by the old value, and multiply by 100. From 80 to 100 is a 25% increase.

Frequently Asked Questions

Why is a 25% increase followed by a 25% decrease not back to the start?

Because each percentage applies to a different base. 100 increased by 25% is 125, and 125 decreased by 25% is 93.75, not 100.

What is the difference between a percentage and percentage points?

If a rate moves from 10% to 12%, it rose by 2 percentage points, but by 20% relative to its old value. The calculator's change mode gives the relative (percentage) change.