Add 15% GST to a price or find the GST inside a total. See the amount before GST, the GST and the total straight away.
This calculator needs JavaScript to run. The sum is simple: to add GST, multiply the price by 1.15. To find the GST inside a total, multiply it by 3 and divide by 23. For example, $100 plus GST is $115, and $100 including GST has $13.04 of GST in it.
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Rounded to the nearest cent. This works out GST on one amount. It does not prepare a GST return.
GST rate checked on 4 November 2026.
To add GST in New Zealand, multiply the price by 1.15. $100 plus GST is $115, of which $15 is GST.
To find the GST inside a GST-inclusive price, multiply it by 3 and divide by 23. $100 including GST has $13.04 of GST in it, so the price before GST is $86.96.
Times 3, divide by 23. That is the whole trick.
The price before GST, the GST at 15% and the price with GST.
| Excl. GST | GST | Incl. GST |
|---|---|---|
| $10.00 | $1.50 | $11.50 |
| $50.00 | $7.50 | $57.50 |
| $100.00 | $15.00 | $115.00 |
| $180.00 | $27.00 | $207.00 |
| $500.00 | $75.00 | $575.00 |
| $1,000.00 | $150.00 | $1,150.00 |
The price with GST, the GST inside it (3/23) and the price before GST.
| Incl. GST | GST | Excl. GST |
|---|---|---|
| $10.00 | $1.30 | $8.70 |
| $50.00 | $6.52 | $43.48 |
| $100.00 | $13.04 | $86.96 |
| $180.00 | $23.48 | $156.52 |
| $500.00 | $65.22 | $434.78 |
| $1,000.00 | $130.43 | $869.57 |
More free tools: GST calculator Australia, GST/HST calculator Canada, VAT calculator.
To calculate GST in New Zealand, multiply the price before GST by 0.15. On $200 the GST is $30, so the total is $230.
To work out the GST exclusive amount, divide the GST-inclusive price by 1.15. $115 including GST is $100 before GST.
3/23 of a GST-inclusive price is the GST inside it. For $100 including GST, that is $13.04.
$180 plus 15% GST is $207, of which $27 is GST.
Yes. EasyInvoice lets you add GST to an invoice, or send one with no tax at all, in minutes from your phone or browser.
You’ve got the GST. Now get paid.
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