NZ GST Percentage Calculator

Calculate 15% GST on a GST-exclusive amount and see the resulting GST-inclusive total. You can also enter an inclusive amount to find its GST component.

Calculate 15% GST

Amount (NZD):

Key formulas

GST on an exclusive amount = amount x 15%. Inclusive total = amount x 1.15. GST contained in an inclusive amount = inclusive x 3 / 23.

Examples

NZ$100 before GST gives NZ$15 GST and NZ$115 including GST. NZ$115 including GST contains NZ$15 GST.

Worked example: adding and extracting 15% GST

A cafe in Nelson sells a coffee machine for $1,150 excluding GST. The GST is $1,150 x 15% = $172.50, so the customer pays $1,322.50 including GST.

Going the other way, a customer brings in a supplier invoice for $1,322.50 including GST and wants the GST component. Multiply by 3/23: $1,322.50 x 3/23 = $172.50 of GST, leaving $1,150.00 before GST. Both directions agree, which is a handy way to check your figures.

When to add GST and when to extract it

Add 15% when you quote or invoice a GST-exclusive price, which is common for business-to-business sales in New Zealand. Extract the GST component when you need to check a supplier’s invoice or work out how much GST you have already paid. Two habits keep the numbers clean:

Label every price as either GST-inclusive or GST-exclusive so there is no guessing later.
Use the 3/23 shortcut for extraction instead of dividing by 1.15 and subtracting. It is faster and avoids rounding drift.

NZ GST percentage calculator FAQs

Is GST 15% in New Zealand?
Yes, the standard rate has been 15% since 1 October 2010. Zero-rated supplies are charged at 0% and exempt supplies carry no GST.

What is the 3/23 rule?
Because 15% GST is 15 parts in 115, the GST inside a GST-inclusive price is 15/115, which simplifies to 3/23. Multiply any GST-inclusive price by 3/23 to find its GST.

Do I add GST to every sale?
No. Add GST to standard taxable supplies. Zero-rated supplies such as exports are charged at 0%, and exempt supplies such as residential rent carry no GST. See the GST-free, zero-rated and exempt guide for the difference.

How should I round GST?
Round to the nearest cent. Standard rounding is accepted by IRD for return purposes.

Scope

The tool is for standard-rate arithmetic. GST treatment can differ for zero-rated and exempt supplies.

NZ GST Calculator · GST-Free / Zero-Rated / Exempt Guide · GST Return Calculator · GST Registration Threshold Guide