Percentage

Percentage calculator

Three everyday questions — X% of Y, X is what % of Y, and percentage change — answered instantly with exact decimal maths and the formula shown underneath.

What is % of ?

50.00

200 × 25 ÷ 100 = 50.00

is what percent of ?

25%

50 ÷ 200 × 100 = 25%

Percentage change from to ?

25%

(250 − 200) ÷ 200 × 100 = 25%

The three modes

Every percentage question is one of three shapes

Most percentage problems reduce to one of three forms. Knowing which one you’re looking at makes the arithmetic obvious — and this calculator lets you switch between them with a tap.

X% of Y25% of 200200 × 25 ÷ 100 = 50

X is what % of Y50 of 20050 ÷ 200 × 100 = 25%

% change200 → 250(250 − 200) ÷ 200 × 100 = +25%

Why decimal-exact matters even here

Ordinary floating-point maths can’t represent numbers like 0.1 exactly, so long chains of percentage steps drift by a cent or a fraction of a point. Everything here runs on exact decimal arithmetic, so the totals reconcile — the same reason our VAT and margin tools stay penny-perfect.

Percentage questions

How do I find X% of Y?

Multiply Y by X and divide by 100. For example 25% of 200 is 200 × 25 ÷ 100 = 50.

How do I work out what percent one number is of another?

Divide the part by the whole and multiply by 100. 50 out of 200 is 50 ÷ 200 × 100 = 25%.

How is percentage change calculated?

Take the new value minus the old, divide by the old, times 100. From 200 to 250 is (250 − 200) ÷ 200 × 100 = +25%. A fall gives a negative result.

What’s the difference between percentage change and percentage points?

A move from 20% to 25% is a rise of 5 percentage points, but a 25% increase in relative terms. This tool reports the relative change; keep the distinction in mind when reading statistics.

Percentage calculator

Every percentage question is one of three shapes

Why decimal-exact matters even here

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