% Percentage Calculator

What is 30% of 40?

30% of 40 is 12. Use the calculator below to change either number, or see related calculations.

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Calculating 30% of 40: divide 30 by 100, then multiply by 40. The general formula is (X ÷ 100) × Y — works for any percentage and any number.

Percentages around this level appear in everyday calculations (interest rates, growth, splits). This base value sits in the everyday range — receipts, tips, small purchases.

How it works.

Formula: (X ÷ 100) × Y.

Step by step:

  1. Divide the percentage by 100: 30 ÷ 100 = 0.3.
  2. Multiply by the number: 0.3 × 40 = 12.
Worked examples
30% of 40 = 12 — the basic calculation: divide 30 by 100 (= 0.3), then multiply by 40.
30% of 40 as a tip on a small bill — if a service charge of 30% is added to a 40 item, the extra is 12.
30% off a 40-pound item — the discount saves 12; the sale price is £28.
Related: 28% of 40 33% of 40 30% of 30 30% of 50 X% of Y calculator

Frequently asked questions

How do I calculate 30% of 40?
Divide 30 by 100, then multiply by 40. 30 ÷ 100 = 0.3; 0.3 × 40 = 12. The same formula works for any pair of numbers.
What is 30 percent of 40?
12. The full calculation: (30 ÷ 100) × 40 = 0.3 × 40 = 12.
What's the difference between a percentage and a percentage point?
A percentage measures a proportion of a whole. A percentage point measures the absolute difference between two percentages. If a tax rate moves from 5% to 7%, that's a 2 percentage point absolute change but a 40% relative increase. UK news often confuses the two when reporting Bank of England rate moves.