Free tool
GST calculator
Type an amount and see the GST both ways: what to add to an ex-GST price, and how much GST is inside a total that already includes it.
Add GST
- GST (10%)
- $100.00
- Total including GST
- $1,100.00
GST inside a total
- GST (one-eleventh)
- $100.00
- Amount excluding GST
- $1,000.00
General information, not tax advice. Confirm current rates and dates on ato.gov.au. Read the guide: bas for sole trader tradies.
Common questions
How do I work out the GST in a total?+
Divide the GST-inclusive amount by 11. A $1,100 invoice contains $100 of GST.
How do I add GST?+
Multiply the ex-GST amount by 1.1. $1,000 plus GST is $1,100.
Do I charge GST?+
Only if you are registered for GST. Registration is compulsory once turnover reaches $75,000 a year; below that it is optional.
Other tools: BAS due dates · Tax set-aside calculator
SmokoBooks does this every day, from your real invoices.
GST position, BAS by quarter and a tax set-aside estimate on the dashboard, worked out from what you actually invoiced and spent. From $19 a month.