FizzyTools
Percentage difference calculator
Compare two numbers as a percentage of their average, with the working. Free, and your numbers never leave your device.
How it works
- 1Pick your questionPercent of a number, change, difference, marks and more.
- 2Type the numbersThe answer appears as you type, exact, with the working.
- 3Copy or shareCopy the answer or the working, or a link that opens the same sum.
Formulas
- P% of X
- X × P ÷ 100
- X is what % of Y
- X ÷ Y × 100
- X is P% of what
- X × 100 ÷ P
- Change from A to B
- (B − A) ÷ |A| × 100 (positive: increase, negative: decrease)
- X increased by P%
- X × (1 + P ÷ 100); decreased: X × (1 − P ÷ 100)
- Original value
- value now ÷ (100 + P) × 100 after adding P%; ÷ (100 − P) × 100 after taking off P%
- Difference of A and B
- |A − B| ÷ ((|A| + |B|) ÷ 2) × 100
- Marks
- total marks ÷ total maximum × 100
- Fraction to percent
- a ÷ b × 100
Sources: the definitions of percent, relative change and percentage point; marks as total obtained ÷ total maximum × 100.
Questions
How do I calculate the percentage difference between two numbers?
Take the difference, divide by the average of the two numbers and multiply by 100. 10 and 20: 10 ÷ 15 × 100 = 66.67%.
Which formula is used?
|A − B| ÷ ((|A| + |B|) ÷ 2) × 100, the common symmetric form. Some fields divide by the larger or the reference value instead; for a before and after, use Percentage change.
How do I work out a percentage of a number?
Multiply the number by the percentage and divide by 100. 20% of 150 is 150 × 20 ÷ 100 = 30.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 45 out of 60 is 45 ÷ 60 × 100 = 75%.
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 80 to 100 is (100 − 80) ÷ 80 × 100 = a 25% increase.
How do I find the original price before a percentage was added?
The price now is 118% of the original (100% + 18%). So divide by 118 and multiply by 100: 1,180 ÷ 118 × 100 = 1,000. Taking 18% off 1,180 gives 967.60, which is wrong, because the 18% was worked out on 1,000. This is also called a reverse percentage.
How do I calculate my marks percentage?
Add up your marks, add up the maximum marks, divide and multiply by 100: 411 out of 500 is 82.2%. Boards and universities may use their own rules, such as best of five subjects, so check your mark sheet.
What is a percentage point?
The plain difference between two percentages. A rate going from 4% to 5% rises by 1 percentage point, which is a 25% increase.
Why does +20% and then −20% not get me back to the start?
The second change is taken from the new, bigger number. 100 + 20% = 120, then 120 − 20% = 96, an overall 4% decrease.
Are the answers exact? How are they rounded?
Every sum is worked out exactly, as a fraction. Only the display is rounded, to the decimal places you choose (2 by default), with halves rounded away from zero. A rounded answer is marked, and shows its exact value, such as 33.3̅% = 1/3.
Are my numbers sent anywhere?
No. Everything is worked out in your browser. A shared link carries the numbers after a #, a part of the link that browsers don't send to servers.