GST calculator
Enter an amount, choose a rate and pick add or remove. The calculator shows the GST-exclusive price, the GST and the GST-inclusive total. Presets cover Australia, New Zealand, the Canadian GST and every HST province at the rates in force in 2026.
Adding and removing GST
- Add GST: inclusive price = exclusive price × (1 + rate). A$500 plus 10% GST is A$550.
- Remove GST: exclusive price = inclusive price ÷ (1 + rate), and GST = inclusive − exclusive. NZ$230 including GST is 230 ÷ 1.15 = NZ$200, so the GST is NZ$30.
Don't simply deduct the rate: 15% off NZ$230 gives NZ$195.50, which understates the exclusive price by NZ$4.50.
Shortcuts for GST-inclusive prices
- Australia, 10%: the GST is the inclusive price ÷ 11, as the ATO explains. A$1,210 including GST contains A$110 of GST.
- New Zealand, 15%: the GST is 3/23 of the inclusive price, because 15/115 simplifies to 3/23. Inland Revenue's example: NZ$100 including GST contains NZ$13.04 of GST.
- Canada: the fraction is rate ÷ (100 + rate): 1/21 for 5% GST, 13/113 for 13% HST and 3/23 for 15% HST.
Canadian GST and HST rates for 2026
These CRA rates have applied since 1 April 2025, when Nova Scotia cut its HST from 15% to 14% (checked September 2026):
| Province or territory | Rate |
|---|---|
| Ontario | 13% HST |
| Nova Scotia | 14% HST |
| New Brunswick, Newfoundland and Labrador, Prince Edward Island | 15% HST |
| Alberta, Northwest Territories, Nunavut, Yukon | 5% GST |
| British Columbia, Manitoba, Saskatchewan | 5% GST plus PST of 7%, 7% and 6% |
| Quebec | 5% GST plus 9.975% QST |
PST and QST are separate provincial taxes, so work them out separately from the GST. Our guides cover Canadian GST/HST invoices and Australian tax invoices.
Frequently asked questions
How do I work out the GST in an Australian price?
Divide the GST-inclusive price by 11. A$99 including GST contains A$9 of GST and A$90 before GST. It works because Australian GST is 10% of the exclusive price, so the inclusive price is 11 parts, one of which is GST.
When do I have to register and charge GST?
In Australia, when your GST turnover is A$75,000 or more (A$150,000 for non-profits). In New Zealand, when turnover was at least NZ$60,000 in the last 12 months or will be in the next 12. In Canada, when taxable revenue goes over C$30,000 in a single calendar quarter or over the last four consecutive quarters.
Which rate applies to a sale between Canadian provinces?
It depends on where the supply is made under the CRA's place-of-supply rules. For goods that is generally where they are delivered, so an Ontario business shipping to a customer in Nova Scotia usually charges 14% HST. Services follow their own rules, so check the CRA guidance.