Based on the 10% GST rate, there is an easy formula to calculate GST in Australia. You can calculate how to add GST on a product(GST-exclusive product) by multiplying the price of the product by 1.1. On the other hand, if you want to know the added amount of GST in a product(GST-inclusive product) by reversing GST calculations, simply divide the product amount by 11. By using this method you will get an idea of how to work out GST from the total price of the product by excluding or including the amount of GST in an item. You can easily find these calculations by using the GST calculator tool. https://findgst.com.au/