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Free GST Tool
GST Calculator NZAdd or Remove 15% GST
Easily add or subtract 15% GST for your invoices and quotes.
NZ GST Calculator (15%)
Instantly add or subtract GST for New Zealand invoices.
Guide
How to Calculate GST in New Zealand
The standard GST rate in New Zealand is 15%. Whether you are a sole trader, contractor, or small business, you need to know how to calculate this correctly for your tax invoices.
Formula to Add GST (Exclusive to Inclusive)
If you have a price before tax and need to add GST:
GST Amount = Price × 0.15
Total Price = Price × 1.15
Formula to Remove GST (Inclusive to Exclusive)
If you have a total price and need to work backwards to find the amount before tax:
GST Amount = Total Price × 3 ÷ 23
Price (Excl) = Total Price ÷ 1.15
Why "Multiply by 3 divide by 23"?
Because 15% is 3/20 as a fraction. The math works out that 3/23 of the total price is the tax component. It is much more precise than using 0.1304...