GST calculator
Add or remove 15% GST from any amount instantly, using the same 3/23 method IRD uses — no rounding drift.
What this means for you
See how much of the total is GST, and how that compares to NZ's historical GST rates.
Compare GST rates over time
NZ's GST rate has risen twice since it began — see how much more tax the same purchase carries today.
| Rate | GST amount | Total price |
|---|---|---|
| 10% (1986-1989) | $0.00 | $0.00 |
| 12.5% (1989-2010) | $0.00 | $0.00 |
| 15% (2010-present) | $0.00 | $0.00 |
Based on the same GST-exclusive price across all three rates, so you can see the tax component alone rising over time.
Assumptions & sources
Inland Revenue (IRD) GST rate and calculation guidance.
1 July 2026
17 July 2026
Exclusive → inclusive: multiply by the rate. Inclusive → exclusive: uses IRD's exact fraction (rate ÷ (100 + rate)) to avoid rounding drift from a simple percentage calculation.
GST calculated at whatever rate you enter, defaulting to the current 15%.
GST-exempt or zero-rated goods and services (e.g. residential rent, financial services), which don't follow the standard calculation.
Related reading
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Read article →
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Rent, groceries, power, petrol — here's what the cost of living conversation actually looks like in the numbers for 2026.
Read article →How NZ GST works
New Zealand charges GST at a flat 15% on almost all goods and services, with no reduced rate for essentials like food — unlike Australia or the UK. The rate has been 15% since 1 October 2010, having risen from 12.5% (1989) and originally 10% (1986).
To add GST to an exclusive price, multiply by 1.15. To find the GST hidden inside an inclusive price, the correct method is to multiply by 3 and divide by 23 (since 15 ÷ 115 simplifies to 3/23) — simply taking 15% of the inclusive total overstates the GST component and is a common mistake.
Example: A sole trader invoicing $2,300 for a landscaping job
Mihi runs a small landscaping business and quotes a client $2,300 for a job, GST-exclusive.
Since she's GST-registered, she needs to add 15% GST to that price: $2,300 × 1.15 = $2,645 total to invoice.
Of that $2,645 invoice, exactly $345 is GST — she can check this using the inclusive-price method: $2,645 × 3 ÷ 23 = $345, which matches.
If she'd mistakenly taken 15% of the $2,645 inclusive total instead — a common error — she'd have gotten $396.75, overstating her GST liability by more than $50.
Frequently asked questions
15%, unchanged since 1 October 2010. There's no reduced rate for essentials, though long-term accommodation (28+ days) is taxed at 9%, and some supplies like residential rent and financial services are GST-exempt.
Multiply the GST-inclusive price by 3 and divide by 23. A $115 GST-inclusive price contains $115 × 3 ÷ 23 = $15 GST — taking a straight 15% of the inclusive total gives the wrong (higher) answer.
