Instant Percentage Calculator
Three modes for the most common percentage calculations in Australia — GST adjustments, retail discounts, salary increases, and investment return comparisons. Results update live as you type.
What is X% of Y?
Example: GST on $450 = $45
X is what % of Y?
Formula: (50 ÷ 200) × 100
% Change from X to Y
📈 Increase of 8,000
How Percentages Work
A percentage represents parts per 100. The three formulas below cover every scenario — from calculating GST and retail discounts to measuring salary growth and investment returns.
Everyday Percentage Uses
- ✔GST (10%): Add GST to a wholesale price by multiplying by 1.10, or find the GST in an inclusive price by dividing by 11.
- ✔Salary increases: Calculate your % raise and compare it to the current Australian CPI (≈ 2.5–3.5% per year).
- ✔Store discounts: A 20% off sale on a $250 item = $50 off → $200 final price.
- ✔Superannuation: The SGC is 11.5% of your ordinary time earnings in 2025/2026.
Frequently Asked Questions
How do you calculate a percentage of a number?
To find X% of Y, use the formula: (X ÷ 100) × Y. For example, 15% of $450 = (15 ÷ 100) × 450 = $67.50. This is the most common percentage calculation in Australia for retail discounts and GST.
How do you calculate GST in Australia?
Australian GST is 10%. To add GST to a price, multiply by 1.10. To find the GST component in a GST-inclusive price, divide by 11. Example: a $110 item includes $10 GST.
What is percentage increase and decrease?
Percentage change = ((New Value − Old Value) ÷ Old Value) × 100. A positive result is an increase; negative is a decrease. Example: salary rising from $80,000 to $88,000 = +10% increase.
How do I calculate a discount percentage?
Discount % = ((Original Price − Sale Price) ÷ Original Price) × 100. Example: item reduced from $200 to $150 = (50 ÷ 200) × 100 = 25% discount.
What percentage is 50 of 200?
50 is 25% of 200. Formula: (50 ÷ 200) × 100 = 25%. The 'X is what % of Y' mode on this calculator solves this instantly.