Reverse GST Calculator
Calculate the original price (before GST) from a GST-inclusive amount
How to Use This Calculator
1
Enter the GST-inclusive amount
This is the total price you've paid, which already includes GST.
2
Select the GST rate
Choose the appropriate GST percentage rate. Common rates are 5%, 10%, 12%, 18%, and 28%, but you can also enter a custom rate.
3
Click "Calculate"
The calculator will determine the original price before GST and the GST amount that was included.
Calculator
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Understanding the Calculation
The reverse GST calculation uses the following formulas:
Original Price = GST-inclusive Price ÷ (1 + GST Rate)
GST Amount = GST-inclusive Price - Original Price
Example:
If you paid $110 for an item including 10% GST:
- Original Price = $110 ÷ (1 + 0.10) = $110 ÷ 1.10 = $100
- GST Amount = $110 - $100 = $10
Why use a Reverse GST Calculator?
This calculator is particularly useful when you need to determine the original price of goods or services when you only know the final price (which includes GST). This is common in business accounting, tax reporting, and understanding price breakdowns.