Percentage Calculator
- Part (20%)
- Rest (80%)
Quick check: 10% of 150 is 15, so 20% is 2 times that.
How the percentage calculation works
Pick the question you need answered
Every percentage problem has three numbers: the part, the whole and the percent. Choose which one you are looking for; you enter the other two.
X% of Y = Y × X ÷ 100
20% of 150 is 150 × 0.20 = 30. Move the decimal point two places to turn a percent into a decimal.
X is what % of Y = X ÷ Y × 100
30 out of 150 is 30 ÷ 150 = 0.2, which is 20%.
The whole = X ÷ (P ÷ 100)
If 30 is 20% of a number, the number is 30 ÷ 0.20 = 150.
Worked example. A customer pays a 20% deposit on a $150 order. 20% of 150 is 30, so the deposit is $30 and $120 is still due. Turned around, 30 is 20% of 150, and if you only know the $30 deposit is 20%, the full order is 30 ÷ 0.20 = 150.
Percentage FAQ
How do you calculate a percentage of a number?
Turn the percent into a decimal and multiply. 20% of 150 is 0.20 × 150 = 30. On a phone calculator, type 150 × 20 % or 150 × 0.2.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. 30 is what percent of 150? 30 ÷ 150 = 0.2, so 20%.
How do I find the whole number from a percentage?
Divide the part by the percent as a decimal. If $30 is 20% of the price, the price is 30 ÷ 0.20 = $150.
What is the formula for percentage?
Percent = part ÷ whole × 100. The same formula, turned around, gives part = whole × percent ÷ 100 and whole = part ÷ percent × 100.
Is X% of Y the same as Y% of X?
Yes. 20% of 150 and 150% of 20 are both 30, because both are 20 × 150 ÷ 100. Use whichever is easier to do in your head.
How do I calculate a percentage increase or decrease?
Subtract the old number from the new one, divide by the old number and multiply by 100. Going from 150 to 180 is 30 ÷ 150 = a 20% increase. The percent change, percentage increase and percentage decrease calculators do this for you.
How do I take a percent off a price?
Multiply the price by 1 minus the percent. 20% off $150 is $150 × 0.80 = $120. The percent off calculator also handles a second, stacked discount.