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Percentage Calculator

Six types of percentage calculations — all with step-by-step solutions. Includes GST, tips, discounts, and percentage change.

1. What is X% of Y?

% of= 30
15% of 200 = (15/100) × 200 = 30

2. X is what % of Y?

is what % of= 15%
30 / 200 × 100 = 15%

3. X is Y% of what?

is% of = 200
30 / (15/100) = 200

4. Percentage Change (increase / decrease)

Fromto= +25%
(100−80)/80 × 100 = +25%

5. Add or Remove Australian GST (10%)

GST rate%
Enter an amount and press Add or Remove GST.

6. Tip & Discount Calculator

Bill / Original price%
Enter values and press a button.

Percentage Formulas

TypeFormula
X% of Y= (X ÷ 100) × Y
X is what % of Y= (X ÷ Y) × 100
X is Y% of what= X ÷ (Y ÷ 100)
% Increase= (New − Old) ÷ Old × 100
% Decrease= (Old − New) ÷ Old × 100
Add GST (10%)= Amount × 1.10
Remove GST (10%)= Amount ÷ 1.10 (or Amount × 10/11)