Percentage of a number
20% of 150 = 20 ÷ 100 × 150 = 30.
Calculate a percentage of a number, find a percentage, measure change or difference, and increase or decrease values with clear formulas.
A percentage expresses a value as a share of 100. Identify the part and reference value before choosing a formula: percentage change uses the original value, while percentage difference treats both values equally.
Convert a percentage to a decimal by dividing by 100, retain full precision during the calculation, and round only the displayed result.
result = (percentage ÷ 100) × valuepercentage = (part ÷ whole) × 100change = ((new − original) ÷ |original|) × 100adjusted = starting × (1 ± percentage ÷ 100)The result is unchanged if A and B are swapped.
difference = |A − B| ÷ ((|A| + |B|) ÷ 2) × 10020% of 150 = 20 ÷ 100 × 150 = 30.
An increase from 100 to 125 is (125 − 100) ÷ 100 × 100 = 25%.
The difference between 80 and 100 is 20 ÷ 90 × 100 ≈ 22.22%.
Divide the percentage by 100, then multiply that decimal by the number. For example, 20% of 150 is 0.2 × 150, which equals 30.
Divide the first number by the comparison number and multiply by 100. The comparison number cannot be zero.
Percentage change compares a new value with an original reference value, so direction matters. Percentage difference compares two values symmetrically and has no original value.
Yes. An increase can exceed 100% when the increase is larger than the magnitude of the original value.
Yes where the formula remains defined. The calculator uses the absolute magnitude of the original value for percentage change and absolute magnitudes in percentage difference.
Those formulas divide by the original or comparison value. Division by zero is undefined, so the calculator asks for a non-zero value.