GST Calculator NZ — Add or Remove 15% GST
Convert a price excluding GST, including GST or stated as GST only. Add quantity and an optional discount, then share, export or print the exact calculation.
Published by GrowThenDraw Editorial Team · Editorial policy · Methodology & sources
| Stage | Excluding GST | GST | Including GST |
|---|---|---|---|
| Per unit after discount | $100.00 | $15.00 | $115.00 |
| Line total (1 unit) | $100.00 | $15.00 | $115.00 |
How to add and remove GST in New Zealand
See the formulas, worked examples, invoice information and scope limits in one place.
Use the NZ PAYE and salary calculator
GST is a consumption tax. Use the PAYE calculator for wages, ACC, KiwiSaver and student-loan deductions.
Add GST to an exclusive price
For a standard-rated price before GST, multiply the exclusive amount by 15% to find the GST. Add that GST to the exclusive price, or multiply the exclusive price by 1.15 to reach the inclusive total.
The calculator applies any entered quantity and discount first, then shows the exclusive subtotal, GST and inclusive total separately so the arithmetic can be checked.
Remove GST from an inclusive price
An inclusive price is not reduced by 15% to remove GST. Divide the inclusive total by 1.15 to find the exclusive value. The GST component is the inclusive total minus that exclusive value; equivalently, it is three twenty-thirds of the inclusive price.
At the standard rate, GST is 15% of the exclusive amount but approximately 13.0435% of the inclusive amount. The result panel makes this distinction explicit.
Use the tool for arithmetic, not tax classification
Inland Revenue's standard GST rate is 15%, but some supplies are zero-rated and others are exempt. Land, exports, financial services and residential accommodation can involve special rules and facts that a price converter cannot decide.
Select this calculator only when 15% GST genuinely applies. Confirm registration, time-of-supply, record-keeping, adjustment and return treatment with Inland Revenue or a qualified adviser.
Frequently asked questions
How do I add 15% GST in New Zealand?
Multiply the GST-exclusive amount by 0.15 to find GST, then add it to the original amount. Multiplying the exclusive amount by 1.15 gives the inclusive total directly.
How do I remove GST from a GST-inclusive price?
Divide the inclusive price by 1.15 to find the exclusive amount. The GST component is the inclusive price minus the exclusive amount, or three twenty-thirds of the inclusive price.
Why is removing 15% not the same as subtracting 15%?
The 15% rate is applied to the exclusive amount. Once GST has been added, GST represents 15/115 of the inclusive total, which simplifies to 3/23 or about 13.0435%.
Does every New Zealand sale have 15% GST?
No. The standard rate is 15%, but some supplies are zero-rated or exempt and other rules can apply. This calculator does not determine a supply's GST treatment.
Does this produce an Inland Revenue-compliant invoice?
No. It calculates amounts only. GST-registered businesses must keep and, where required, provide the taxable supply information specified by Inland Revenue.
New Zealand GST rules and records guidance verified 2026-08-11:
- Inland Revenue: calculating GST at the 15% standard rate
- Inland Revenue: taxable supply information and amount fields
- Inland Revenue: zero-rated supplies
- Inland Revenue IR375 GST guide, March 2026
Method: quantity and discount are applied to the selected amount first. A standard-rated exclusive amount uses × 0.15 for GST; an inclusive amount uses ÷ 1.15 for the exclusive value; a GST-only amount uses ÷ 0.15 for the exclusive value. Displayed currency is rounded to cents, while the engine retains full precision.
Excluded: deciding whether a supply is taxable, zero-rated or exempt; GST registration; time-of-supply rules; mixed supplies; secondhand goods; imports, exports, land and remote services; private-use adjustments; return filing; invoice issuance; credit/debit corrections and transaction-level rounding policies. Educational arithmetic tool only, not tax, accounting or legal advice.