Percentage Calculator
Find percentages, proportions, and percentage changes.
What is X% of Y?
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Supports negative values and decimals. Results are rounded to 12 significant digits.
How to use Percentage Calculator
- Choose the calculation that matches your question.
- Enter both values. For percentage change, enter the original value first and the new value second.
- Read the result and formula to see how the calculation works.
What is Percentage Calculator?
A percentage expresses a quantity out of 100. To find X% of Y, multiply Y by X ÷ 100. To express X as a percentage of Y, calculate X ÷ Y × 100. Percentage change compares a new value with its original value, using (new − original) ÷ |original| × 100. Using the original value's magnitude keeps the sign aligned with the direction of change when the original value is negative.
- Calculate a percentage of any finite number
- Express one value as a percentage of another
- Calculate percentage increase or decrease
- See the formula alongside the result
A practical example
What is 15% of 200?
15 ÷ 100 × 200 = 30
Frequently asked questions
How do I calculate a percentage increase?
Subtract the original value from the new value, divide by the absolute value of the original, then multiply by 100. For example, a change from 80 to 100 is a 25% increase. Interpret changes from a negative starting value with care, since conventions vary.
Why can I not use zero as the original value?
Percentage change divides by the original value. Division by zero is undefined, so a change from zero cannot be expressed as a standard percentage change.
Are percentage changes the same as percentage points?
No. A rate moving from 10% to 15% rises by 5 percentage points and by 50% relative to its original value. This calculator reports relative percentage change.
Can I calculate a discount?
Yes. Calculate the discount percentage of the original price to find the amount saved. Subtract that result from the original price to find the discounted price.