GST Calculator
Goods and services tax (GST) is a value-added tax used in Australia, New Zealand, Canada, Singapore, India and a number of other countries. It works the way VAT does: the price you see may or may not include it, and businesses regularly need to convert between the price with GST and the price without. This calculator adds GST, removes GST or finds the rate from a pair of prices, with presets for Australia (10%), New Zealand (15%) and Canada’s 5% federal GST. In Canada, provinces add their own sales tax or use a combined HST, so for a final price enter your province’s combined rate as a custom rate.
How to use the gst calculator
- Choose whether to add GST, remove GST or find the rate.
- Enter the amount, then pick the preset for your country or choose Custom and enter your rate.
- Read the net amount, GST and gross amount.
- Confirm the current rate and which goods qualify with your national tax authority before filing or invoicing.
Formula
Gross = net × (1 + GST rate). GST = net × rate. Net = gross ÷ (1 + rate). At 10% (Australia), GST is exactly one-eleventh of the gross price; at 15% (New Zealand), it is three-twenty-thirds. Implied rate = (gross ÷ net − 1) × 100.
Worked examples
Australia — 10%
A$110 including 10% GST has A$10.00 of GST on a net price of A$100.00 — the “divide by 11” shortcut.
New Zealand — 15%
Adding 15% GST to NZ$200 gives A$230.00 (GST A$30.00). Choose NZD-style formatting by selecting the closest currency; the arithmetic is identical.
A custom combined rate
For a province with a 13% combined rate, enter 13 as a custom rate: a C$80 price becomes CA$90.40 including tax.
GST in different countries
Australia (10%), New Zealand (15%) and Canada (5% federal) all use a goods and services tax, but the design differs. In Australia, some basic foods and medical items are GST-free. In New Zealand GST applies to almost everything with few exceptions. In Canada, the five percent federal GST is joined by provincial taxes or replaced by a combined HST, so the all-in rate depends on the province.
Shortcuts
- Australia (10%): GST in a gross price is gross ÷ 11.
- New Zealand (15%): GST in a gross price is gross × 3 ÷ 23.
See also the VAT calculator and the invoice generator.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- A$330 includes 10% GST. How much is the GST?
Show answer
Price before tax (net): A$300.00 · GST included: A$30.00
Common mistakes to avoid
- Subtracting the rate from the gross price. Divide by (1 + rate) instead.
- Treating Canada’s 5% federal GST as the full tax. Most provinces add PST or use a combined HST — enter the combined rate for a final price.
- Using an old rate. GST rates and the goods they apply to change; check your tax authority.
- Confusing “GST-free” (zero-rated, e.g. some food in Australia) with “out of scope”. They have different effects on claiming credits.
- Forgetting to register once your turnover passes the registration threshold, where you must charge GST.
Frequently asked questions
How do I calculate GST?
Multiply the net price by the GST rate to get the tax, and add it to get the gross price. At 10%, a $100 item has $10 GST and costs $110.
How do I take GST out of a price?
Divide the gross price by 1 plus the rate. For 10% GST, divide by 1.1, or take one-eleventh of the gross as the GST.
What is the GST rate in New Zealand?
New Zealand charges GST at 15% on most goods and services, according to Inland Revenue.
What is the GST rate in Australia and Canada?
Australia charges 10% and Canada’s federal GST is 5%, with provinces adding their own taxes. Check the ATO and the Canada Revenue Agency for current details.
Does this calculator work for India’s GST?
You can use it with a custom rate, but India’s GST has multiple slabs and rules that change; a dedicated India GST calculator is planned.
Is this tax advice?
No. It is a calculator for everyday use; check treatment with your tax authority or accountant.
Sources and further reading
By Thomas M, Registered Investment Adviser (South Carolina), who launched his own financial advisory firm in 2010. Last reviewed September 26, 2026. Found a mistake? Tell us; see our editorial policy.