English
العربية
Deutsch
Español
Français
Italiano
Português
Русский
Türkçe
Tiếng Việt
GST Calculator
Add GST to a price or work out the GST inside a total.
GST calculations come in two directions, and the second one catches people out. Adding GST is straightforward multiplication. Finding the GST already inside a total requires division, and subtracting the percentage instead will give you the wrong answer every time.
Both directions
- Enter your amount.
- Enter the GST rate that applies.
- Choose whether the amount is exclusive of GST or already includes it.
- Read the GST amount and the other figure.
- Use the exclusive mode for quoting and the inclusive mode for reconciling receipts.
Extracting GST from a gross amount
If a bill totals 1,180 including 18% GST, the GST is not 18% of 1,180. Divide instead: 1,180 ÷ 1.18 = 1,000 net, so the GST component is 180.
The general rule is gross ÷ (1 + rate) = net. At 10% you divide by 1.1; at 15% by 1.15. Getting this backwards inflates your reported net revenue and understates the tax you owe, which is the kind of error that surfaces at an awkward moment.
Common GST rates
| Country | Standard rate | Divide gross by |
|---|---|---|
| Australia | 10% | 1.10 |
| New Zealand | 15% | 1.15 |
| Canada (federal GST) | 5% | 1.05 |
| Singapore | 9% | 1.09 |
| India | 5 / 12 / 18 / 28% | 1.05 / 1.12 / 1.18 / 1.28 |
Points worth checking locally
- Whether your displayed prices must include GST — consumer rules vary.
- Which rate slab applies to your specific goods or services.
- The registration threshold below which you do not charge GST at all.
- Whether you can claim input credits on business purchases.
- Provincial or state taxes layered on top of a federal rate, as in Canada.
GST questions
How do I add GST to a price?
Multiply the net amount by the rate and divide by 100 for the GST, then add it on. Or multiply by (1 + rate) to get the total directly: 500 at 10% becomes 550.
How do I calculate the GST inside a total?
Divide the gross by (1 + rate) to get the net, then subtract. A total of 550 including 10% GST breaks down as 500 net and 50 GST. Taking 10% off 550 gives 495, which is wrong.
Is GST the same as VAT?
Functionally very similar — both are multi-stage consumption taxes with input credits. The name differs by country, and the detailed rules on rates, exemptions and registration vary considerably.
What are input tax credits?
GST-registered businesses can generally reclaim the GST paid on business purchases, offsetting it against the GST they collect. The net effect is that the tax falls on the final consumer.
Which rate should I use?
Whichever applies to your goods or services in your jurisdiction. India in particular uses several slabs depending on the category, so check the classification rather than assuming a single rate.
