GST calculator
Add GST to a price or separate the tax already included. Enter the rate that applies to your transaction.
- GST added to net amount
- 120.00
- Gross amount
- 920.00
- GST included in entered amount
- 104.35
- Net amount if GST-inclusive
- 695.65
What this calculator works out
This is for businesses in GST systems that need a quick price check before preparing a quote, invoice or expense record.
Calculation: GST to add = net amount × rate. GST included = gross amount − gross amount ÷ (1 + rate).
Practical example
At a 15% rate, a net price of 800 produces 120 GST and a gross price of 920. If 800 is already GST-inclusive, the included GST is 104.35—not 120.
Use the result carefully
- Use the current rate that applies in your jurisdiction; the calculator does not choose it for you.
- Registration, exemptions and invoice wording depend on local rules.
- Keep net, tax and gross figures clearly separated on the final document.