/
A quick guide on how to figure out GST amounts for your invoices, whether you need to add it on or extract it from a total.
Calculate your numbers instantly in your browser. Fast, free, no signup.
Whether you are a freelancer generating an invoice, a small business owner pricing your products, or a consumer checking a receipt, calculating the Goods and Services Tax (GST) is a constant necessity.
However, calculating GST isn't always as simple as multiplying by a percentage—especially when you need to find the base price of an item where GST is already included.
If you have a base price of $100 and the GST rate is 18%, the math is simple:
Base Price × 1.18 = Total Price ($118).
If you have a total price of $118 and want to find the original base price before 18% GST was added, you cannot just subtract 18%.
The correct math is:
Total Price ÷ 1.18 = Base Price ($100).
Instead of fumbling with your phone calculator and getting the inclusive math wrong, use our Free GST Calculator.
Bookmark the tool today and make invoicing a breeze!