Percentage Calculator

A percentage describes a quantity per hundred. For example, 20% means 20 out of every 100, or 0.2 as a decimal.

• Percent of a number: value × percent ÷ 100.
• What percent: part ÷ whole × 100.
• Percentage change: (new − old) ÷ old × 100.

Convert the percentage to a decimal by dividing by 100, then multiply by the number. Thus, 20% of 150 is 150 × 20 ÷ 100 = 30.

Divide the part by the whole and multiply by 100. For example, 45 ÷ 300 × 100 = 15%. The whole cannot be zero.

Subtract the starting value from the new value, divide by the starting value, and multiply by 100. This calculator requires a positive starting value so the interpretation remains clear.

An increase adds the percentage portion to the base; a decrease subtracts it. A decrease above 100% can cross zero and produce a negative result.

A price of 200 increased by 12.5% becomes 225. The same base decreased by 12.5% becomes 175. A value moving from 50 to 75 is a 50% increase.

Do not confuse a percentage change with a percentage-point change. Check which value is the whole, and remember that reversing old and new values changes the result.

Can a percentage exceed 100%?

Yes. It can describe a quantity larger than the reference amount. Percentage inputs can exceed 100 where the operation makes mathematical sense.

Are decimals supported?

Yes. You can enter decimal values in every mode.