Percentage calculator

25% of 80 is 20: multiply by the percent, then divide by 100. Pick your question, type your numbers, and the answer appears with the formula filled in.

What is X% of Y?

%

Negative numbers and decimals work. Percentages are shown to two decimal places, other numbers to four.

The three formulas

Every percent question is one of these. The calculator shows the one it used with your numbers plugged in.

  1. X% of YX ÷ 100 × Y. For 25% of 80: 25 ÷ 100 × 80 = 20.
  2. X is what percent of YX ÷ Y × 100. For 18 out of 24: 18 ÷ 24 × 100 = 75%.
  3. Percent change from X to Y(Y − X) ÷ X × 100. From 80 to 60: (60 − 80) ÷ 80 × 100 = −25%, a 25% decrease.

Worked examples

Each answer comes from the same math as the calculator above.

  1. What is 20% of 150?

    20% of 150 is 30.

    20 ÷ 100 × 150 = 30

  2. What is 15% of 80?

    15% of 80 is 12.

    15 ÷ 100 × 80 = 12

  3. What is 7.5% of 2,400?

    7.5% of 2,400 is 180.

    7.5 ÷ 100 × 2,400 = 180

  4. 45 is what percent of 60?

    45 is 75% of 60.

    45 ÷ 60 × 100 = 75%

  5. 1 is what percent of 3?

    1 is about 33.33% of 3.

    1 ÷ 3 × 100 ≈ 33.33%

  6. 18 is what percent of 24?

    18 is 75% of 24.

    18 ÷ 24 × 100 = 75%

  7. What is the percent change from 50 to 65?

    Going from 50 to 65 is a 30% increase (a change of +15).

    (65 − 50) ÷ 50 × 100 = +30%

  8. What is the percent change from 80 to 60?

    Going from 80 to 60 is a 25% decrease (a change of −20).

    (60 − 80) ÷ 80 × 100 = −25%

Common percentages

Quick answers for the percents people use most.

Common percentages of common numbers
Percentof 20of 50of 80of 200
5%12.5410
10%25820
15%37.51230
20%4101640
25%512.52050
30%6152460
50%102540100
75%1537.560150

Questions

How do I calculate a percentage of a number?
Multiply the number by the percent, then divide by 100. For 25% of 80, that is 25 × 80 ÷ 100 = 20.
How do I find what percent one number is of another?
Divide the part by the whole, then multiply by 100. For 18 out of 24, that is 18 ÷ 24 × 100 = 75%.
How do I calculate percent change?
Subtract the old value from the new one, divide by the old value, and multiply by 100. From 50 to 65 is (65 − 50) ÷ 50 × 100 = 30%, an increase. A negative answer is a decrease.
Why can't I get a percent change from 0?
Percent change divides by the starting value, and nothing can be divided by 0. Going from 0 to 5 is a change of 5, but it has no percent. Use the actual difference instead.
Is X% of Y the same as Y% of X?
Yes. 8% of 50 and 50% of 8 are both 4, because the multiplication works in either order. Swapping can make mental math easier.

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