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How do I work out what percentage one number is of another, like 27 out of 40?

Short answer

Divide the part by the whole and multiply by 100. So 27 out of 40 is 27 divided by 40, which is 0.675, or 67.5 percent. A free browser-based percentage calculator does the same division instantly for any pair of numbers.

The formula

Percentage means per hundred, so the question is always part divided by whole, times 100. A score of 27 out of 40 is 27 / 40 x 100 = 67.5 percent. A bill of 45 out of a 60 budget is 75 percent. The same formula covers test scores, attendance, progress toward a goal, and how much of a total any single item represents.

Do not mix up the two percentage questions

People ask two different things: what percent is X of Y (27 out of 40 is 67.5 percent), and what is X percent of Y (27 percent of 40 is 10.8). The first divides, the second multiplies by the rate. A percentage calculator that offers both modes keeps you from applying the wrong one.

For test scores specifically

If you are grading, a test score calculator takes the number of questions and how many were right or wrong, and returns the percentage and a letter grade in one step. It runs entirely in your browser with no sign-up.

Step by step

  1. Enter the part. Type the smaller number, for example the points you scored.
  2. Enter the whole. Type the total it is out of, for example the maximum points.
  3. Read the percentage. The calculator divides and multiplies by 100 for you and shows the percent instantly.

Frequently asked questions

What percentage is 45 out of 60?

45 divided by 60 is 0.75, so 45 out of 60 is 75 percent.

What is the general formula?

Percent = part / whole x 100. It works for any part and whole where the whole is not zero.

Is my data sent anywhere?

No. The calculation runs entirely in your browser, nothing is uploaded or stored.

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