Ratio Calculator
Percentage Calculator
"Percent" is a unit for expressing a ratio out of 100, derived from the Latin "per centum"...
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Percentages are proportions written out of one hundred, and almost every mistake comes from the base — the number the percentage is taken from. The page makes the base explicit: it asks what the percentage is of, and returns the part, the whole or the rate depending on what you leave empty.
Percentage change is a different question from percentage of. A price rising from 80 to 100 is a 25 % increase, while falling from 100 to 80 is a 20 % decrease: the same 20 units, two different bases.
Frequently Asked Questions
What is the difference between percentage points and percent?
A rate moving from 4 % to 5 % rises by one percentage point, but by 25 % in relative terms. Central-bank statements mean points; headlines often mean percent.
Why is a 50 % discount not cancelled by a 50 % increase?
Because the second percentage applies to the smaller number. 100 discounted by half is 50; a 50 % increase on 50 is 75, not 100.
How do I find the original price after a discount?
Divide by one minus the rate. After 20 % off, dividing the sale price by 0.8 returns the original; taking 20 % of the sale price gives the wrong answer.
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Sources & last update
2026-10-19