Math & Algebra
Percentage Calculator
Solve common percentage problems: percent of a number, percent change, ratios, and increase or decrease.
Educational estimates only. Not medical, legal, tax, or financial advice.
Guide: Percentage Calculator
What it does
Handles everyday percentage math for classwork, discounts, marks, pricing, and quick comparisons.
How to use it
Choose the calculation type, enter the two values, and the result updates immediately.
Formula
p% of n = (p / 100) x n; percent change = (new - old) / old x 100.
Example
20% of 50 is 10. If 80 increases to 100, the percentage change is 25%.
FAQs
How do I calculate a percentage of a number?
Multiply the number by the percentage divided by 100. For example, 20% of 50 is 50 x 0.20 = 10.
Why is percentage change negative?
Percentage change is negative when the new value is lower than the original value.
Should I round percentage answers?
Round only for display or school instructions. Keep full precision while doing intermediate calculations.