InvioGST Calculator NZAdd or Remove 15% GST
Easily add or subtract 15% GST for your invoices and quotes, then use the same numbers when you build a tax invoice.
How much is GST in NZ?
The standard New Zealand GST rate is 15% for most goods and services.
Add GST formula
GST-inclusive total = amount × 1.15. GST only = amount × 0.15.
Remove GST formula
GST-exclusive amount = total ÷ 1.15. GST component = total × 3 ÷ 23.
NZ GST Calculator (15%)
Instantly add or subtract GST for New Zealand invoices.
Common NZ GST Calculator Examples
These are the exact calculations people usually need before creating a GST invoice, quote, or tax record.
Add GST to $100
$100 × 1.15 = $115 total, with $15 GST.
Remove GST from $115
$115 ÷ 1.15 = $100 before GST.
Find GST inside $115
$115 × 3 ÷ 23 = $15 GST component.
Calculate GST only
GST-exclusive amount × 0.15 gives the GST amount.
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 calculate it correctly so the invoice totals and GST breakdown line up.
Formula to Add GST in NZ (Exclusive to Inclusive)
If you have a price before tax and need to add GST:
Formula to Remove GST in NZ (Inclusive to Exclusive)
If you have a total price and need to work backwards to find the amount before tax:
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...
Need to understand your broader GST obligations? See our Sole Trader Tax Guide for GST thresholds and registration requirements, or the NZ Tax Invoice Requirements guide for exactly what must appear on a valid GST invoice. Also wondering how much income tax to set aside on top of GST? Use our NZ Income Tax Calculator to see your exact set-aside percentage for the 2025-26 tax year.
If you are still choosing a workflow, browse the full resources hub or read our comparison of free invoicing software in NZ to see when a quick calculator is enough and when saved client data starts to matter.
GST Calculator for Sole Traders and Small Businesses
GST-registered sole traders and small businesses must add 15% GST to invoices and collect it on behalf of IRD. Use this calculator when you are quoting a job to show the GST-exclusive price alongside the GST-inclusive total, or when you need to confirm the GST component on a supplier receipt before claiming it back.
The most common use case is quoting: enter your labour or materials cost, hit "Add GST", and you have the exact figures to put on your quote or invoice. Once you have your totals, you can move straight to invoicing. Need a ready-made layout? Download our free tax invoice template to drop your calculated totals straight into a GST-ready document, or use Invio invoicing software to create and send a GST invoice in under 60 seconds.
If you are not yet registered for GST, the calculator is still useful for understanding the tax component in supplier invoices and for planning ahead when you approach the $60,000 threshold.