Percentage Calculator
Percent of, percent change and more.
Percent of, percent change and more.
Choose percentages, GCF and LCM, quadratic equations or the Pythagorean theorem.
Percent of, percent change and more.
Greatest common factor, least common multiple.
Open calculatorRoots of ax² + bx + c = 0.
Open calculatorHypotenuse from two sides.
Open calculatorPercentages show up everywhere — discounts, grades, tax, tips, statistics — yet the three basic percentage questions are surprisingly easy to mix up. This calculator answers all three at once from just two numbers: what is A% of B, what percentage of B is A, and what is the percent change from A to B.
Enter any two values. The calculator computes all three relationships simultaneously so you never have to remember which formula fits your question — just read the line that matches what you asked.
The first formula scales B by the percentage A. The second expresses A as a share of B. The third measures relative growth or decline from A to B.
With A = 25 and B = 200: 25% of 200 is 50; 25 is 12.5% of 200; and going from 25 to 200 is a 700% increase. Three different questions, three different answers, from the same two numbers.
Because the second percentage applies to a new, larger base. 100 increased by 50% is 150; decreasing 150 by 50% gives 75, not 100. Percentage changes are relative to their starting point.
Going from 10% to 15% is a rise of 5 percentage points, but a 50% relative increase. News reports often confuse the two — knowing the difference protects you from misleading statistics.
If a price after a 20% discount is 80, the original was 80 ÷ (1 − 0.20) = 100. Divide by (1 ± rate), don't multiply — a common trap.
These sources are used to verify terminology, formulas, and information related to this calculator.