Percentage Calculator
Answer the three everyday percentage questions in one place. Pick what you want to work out — what X% of a number is, what percent one number is of another, or the percent change between two numbers — and the answer updates as you type.
Enter values above to see the result.
The three questions
Most everyday percentage problems are one of three:
- What is X% of a number? — a tip, a tax, a share of a total.
- X is what percent of Y? — a score, a portion, a completion rate.
- Percent change from X to Y — a price rise, a discount, growth over time.
Pick the one you need from the dropdown and only its inputs appear.
The formulas
X% of a number = (percent ÷ 100) × number
X is what % of Y = (X ÷ Y) × 100
percent change = ((new − old) ÷ old) × 100
A worked example
Say a $80 jacket is marked 15% off, and you want the discount in dollars.
That's the first question — what is 15% of 80:
15 ÷ 100 = 0.15
0.15 × 80 = 12
So the discount is $12, and you'd pay $68.
Now suppose the price later rises from $68 to $85 and you want the increase as a percent. That's the change mode:
85 − 68 = 17
17 ÷ 68 = 0.25
0.25 × 100 = 25%
A 25% increase.
Why percent change isn't symmetric
Going up from 200 to 250 is a 25% increase, but coming back down from 250 to 200 is a 20% decrease — not 25%. The percentage is always measured against the starting number, and the starting number is different in each direction. That's why a stock that drops 50% has to gain 100% just to get back to where it began.
Frequently asked questions
How do I work out X% of a number?
Divide the percentage by 100 and multiply by the number. So 15% of 80 is 0.15 × 80 = 12. Use the first mode, enter the percentage and the amount, and the calculator does it for you.
How do I find what percent one number is of another?
Divide the first number by the second and multiply by 100. For example, 45 out of 60 is 45 ÷ 60 × 100 = 75%. That's the second mode — enter the value and the total.
What's the difference between percent change and percentage points?
Percent change compares two numbers relative to the starting one: going from 200 to 250 is a 25% increase. Percentage points are the plain gap between two percentages — a rate that moves from 40% to 45% has risen 5 percentage points, not 12.5%. This calculator's change mode gives you the percent change.
How is a percent increase different from a percent decrease?
Both use the same formula — the change divided by the original value — but the result is positive when the number goes up and negative when it goes down. Going from 200 to 250 is +25%; going back from 250 to 200 is −20%, not −25%, because the starting number is larger the second time.