GST Calculator
Add GST to a net price or back out GST from a tax-inclusive price in one click.
Mode
GST rate
180
1,000
1,180
Formula
About this calculator
Goods and Services Tax (GST) is a value-added tax applied to most goods and services. In "add" mode you start with a net (pre-tax) price and the calculator adds the chosen rate to give the gross, tax-inclusive total. In "remove" mode you start with a gross price that already includes GST and the calculator works backwards to reveal the original net amount and the tax portion.
Removing GST is not the same as simply subtracting the rate. Because the tax was applied on top of the net amount, you must divide the gross by (1 + rate ÷ 100). For example, removing 18% from 1,180 gives a net of 1,000 and GST of 180 — not 1,180 minus 18%.
Frequently asked questions
Divide the tax-inclusive price by 1.18. The result is the net amount; the difference is the GST.
GST was added to the smaller net amount, so subtracting 18% of the larger gross figure overshoots. Dividing by 1.18 reverses it exactly.
The common slab rates of 5%, 12%, 18% and 28% are provided in the dropdown.
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