How to Calculate GST: Adding and Removing Tax
A step-by-step guide on how to manually calculate GST, including formulas for adding GST to a base price and extracting it from a total.
Adding GST to a Base Price
To calculate the GST amount to add to a base price (exclusive of tax), multiply the base price by the GST rate. Then, add the GST amount to the base price to find the total gross amount.
Formula:
GST Amount = Base Price × (GST Rate / 100)
Total Gross Amount = Base Price + GST Amount
Removing GST from a Total Price
To extract the GST amount from a total price (inclusive of tax), divide the total price by 1 plus the GST rate (expressed as a decimal). This gives you the base price. Subtract the base price from the total price to find the GST amount.
Formula:
Base Price = Total Price / (1 + (GST Rate / 100))
GST Amount = Total Price - Base Price
Using a GST Calculator
While manual calculations are useful, using a dedicated GST calculator like ours ensures accuracy and saves time. Simply enter the amount, select the rate, and choose whether to add or remove GST.