Percentage Calculator — what percent one number is of another

How it works

A percentage expresses one quantity as a share of another, scaled so the whole is 100. The symbol % stands for the number 0.01 — "percent" literally means "per hundred" — so asking "what percent is the part of the whole?" is just asking how many hundredths of the whole the part represents:

percentage = (part ÷ whole) × 100

Dividing the part by the whole gives a fraction between 0 and 1 (or more, if the part is larger than the whole); multiplying by 100 restates that fraction out of a hundred. That's the entire operation — there's nothing approximate about it, which is why this works identically for test scores, discounts, survey results or any other "X out of Y" question.

Worked example

Suppose you scored 68 out of 80 on a test:

percentage = (68 ÷ 80) × 100 = 0.85 × 100 = 85%

A few more to show the pattern: 25 out of 200 is 0.125 → 12.5%; a part equal to the whole (50 out of 50) is 100%; and a part larger than the whole (120 out of 80) is 150%, since the part is one-and-a-half times the whole.

Frequently asked questions

How do I calculate a percentage?

Divide the part by the whole and multiply by 100. If 30 people out of 120 chose an option, that's 30 ÷ 120 = 0.25 → 25%. The part is the amount you're measuring; the whole is the total it's being compared against.

What's the difference between "part" and "whole"?

The **whole** is the total — the 100% reference — and the **part** is the slice of it you're expressing. In "what percent of the class passed?", the whole is the number of students and the part is the number who passed. Getting them the right way round matters: 20 out of 50 is 40%, but 50 out of 20 is 250%.

Can a percentage be more than 100% or negative?

Yes. If the part is larger than the whole the percentage exceeds 100% — 120 out of 80 is 150%. And if the part is negative (a loss, say, against a positive total), the percentage is negative. Only the whole being **zero** has no answer, because you can't take a share of nothing.

Why does dividing by the whole come first?

Because the percentage is defined relative to the whole: part ÷ whole tells you the fraction, and ×100 just re-expresses that fraction per hundred. You can do the ×100 first if you prefer — (part × 100) ÷ whole gives the same result — since multiplication and division can be reordered freely.

How is this different from "percent of a number" or "percent change"?

This page answers "**what percent** is A of B?" and gives a percentage. Finding "what **is** 15% of 80?" runs the other way and gives an amount — use the percent of a number calculator. Comparing two values as a rise or fall ("from 50 to 75") is a percent **change** — a third, related question with its own page.

How do I turn a fraction or decimal into a percentage?

Multiply by 100 and add the % sign. The fraction 3/8 is 0.375, which is 37.5%; the decimal 0.6 is 60%. Going the other way, divide the percentage by 100 to recover the decimal — that's the same "part ÷ whole" operation, just with the whole already scaled to 1.