Percentage Calculator
Work out X percent of a number, what percentage one number is of another, or the percentage increase or decrease from an old value to a new one.
Result
30
X% of Y
Percentage as a decimal
0.15
Difference
170
Please note: The result is an estimate and has been rounded. Actual costs and values may differ, and no rights can be derived from this calculation.
How this number is calculated
The blocks use your input. Change a value above and they update with it.
Step 1 · Result of the chosen sum
Step 2 · Percentage as a decimal
Step 3 · Difference
How the calculation works
This calculator handles the three most common percentage sums: what X percent of Y is, what percentage X is of Y, and by what percentage a value changes when it goes from X to Y.
Percent means per hundred. X% of Y is X times Y divided by 100. To find what percentage X is of Y, divide X by Y and multiply by 100. The percentage change is the new value minus the old value, divided by the old value and multiplied by 100. A negative result is a decrease. With a negative old value, the calculator divides by the value without its minus sign, so an increase is always positive. If Y or the old value is 0, there is no percentage and the calculator shows 0. For X% of Y, the difference is what is left of Y after taking off the result; for the other two sums it is Y minus X. The result and the difference are rounded to two decimal places, the decimal to four.
Formula
X% of Y = X × Y ÷ 100. X is ?% of Y: X × 100 ÷ Y. From X to Y: (Y − X) × 100 ÷ X (without its minus sign).
Assumptions
- For From X to Y, X is the old value: the change is a percentage of X.
- If the whole or the old value is 0, there is no percentage and the calculator shows 0.
- With a negative old value, the calculator divides by the value without its minus sign.
- The result and the difference are rounded to two decimal places, the decimal to four.
Example calculations
The button fills in the calculator above, so you can carry on from there.
-
A 30% deposit
Result
360
X% of Y · Value X 30 · Value Y 1,200
-
Test score
Result
84
X is ?% of Y · Value X 42 · Value Y 50
-
Pay rise as a percentage
Result
4
From X to Y · Value X 2,850 · Value Y 2,964
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. 15% of 200 is 15 × 200 ÷ 100 = 30. Or multiply 200 by 0.15, which is 15% as a decimal.
How do I work out what percentage one number is of another?
Divide the part by the whole and multiply by 100. 30 out of 200 is 30 ÷ 200 × 100 = 15%. If the part is bigger than the whole, the result is over 100%.
How do I calculate a percentage increase or decrease?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 200 to 230 is a 15% increase, from 80 to 60 is a 25% decrease.
What is the difference between a percentage and a percentage point?
A percentage point is the plain difference between two percentages. If an interest rate goes from 2% to 3%, it rises by 1 percentage point, which is an increase of 50 percent.
How do I find the whole if I know the part and the percentage?
Divide the part by the percentage and multiply by 100. If 30 is 15% of a number, that number is 30 ÷ 15 × 100 = 200.
Why does adding 10% and then taking 10% off not bring you back to the start?
The second percentage is taken of a different number. 100 plus 10% is 110, and 10% of 110 is 11, so you end up at 99.
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