Toolzaio Percentage Calculator
Three everyday questions, answered as you type: a percentage of a number, one number as a share of another, and the change between two numbers.
What is X% of Y?
Type both numbers to see the answer.
X is what percent of Y?
Type both numbers to see the answer.
Percentage change from X to Y
Type both numbers to see the answer.
How it works
A percentage is a fraction out of a hundred. The first box multiplies: 20% of 150 means 150 × 20 ÷ 100, which is 30. That is the maths behind discounts, tips and exam marks. If a jacket is 20% off at 150, you take 30 off and pay 120.
The second box divides: score 45 out of 60 and your share is 45 ÷ 60 × 100, which is 75%. The third box compares a start and an end value. Going from 80 to 100 is a rise of 20, and 20 as a share of the start value is 25%, so the change is +25%. Going down works the same way and shows as a negative number.
Everything is worked out on your device as you type. No numbers are saved or sent anywhere.
Questions people ask
How do I work out a discount quickly?
Use the first box: type the discount percentage and the price. The answer is the amount taken off. Take it away from the price to get what you actually pay.
What is the difference between percent and percentage points?
If an interest rate moves from 4% to 5%, it rose by 1 percentage point, but by 25% in relative terms. News reports mix these up often; the third box above gives the relative change.
Can the answer be more than 100%?
Yes. If the part is bigger than the whole, the share is over 100%. And a value that more than doubles has risen by more than 100%.
Why does dividing by zero show no answer?
A share of nothing cannot be worked out, and neither can a change from zero. If either box needs a zero where the other number divides by it, the calculator waits for a usable number instead of showing nonsense.
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