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GST on $50

Both answers, because "GST on $50" means two different things depending on whether that figure already includes GST.

NZ 15% and AU 10% Add or remove GST Sends straight to an invoice
$
Total including 15% GST
$57.50
NZD · rounded to the cent

SOURCE·IRD — GST rate 15% since 1 Oct 2010·REVIEWED JUL 2026

3/23 of a 15%-inclusive total is GST — 13.04%, not 15%. Inland Revenue, ird.govt.nz/gst, reviewed JUL 2026.
Excluding GST$50.00
GST$7.50
Including GST$57.50
Next step Put this on a GST tax invoice → With your business details and the GST number IRD wants.

How much GST is on $50?

  • If $50 is before GST: GST is $7.50 and the total becomes $57.50.
  • If $50 already includes GST: the GST portion is $6.52 and the price before GST is $43.48.
  • Working: $50.00 × 1.15 = $57.50  ·  $50.00 ÷ 23 × 3 = $6.52

SOURCE·IRD — GST rate 15% since 1 Oct 2010·REVIEWED JUL 2026

How this is worked out

  1. Decide which side of GST your figure sits on: exclusive (GST not added yet) or inclusive (GST already inside it). Every GST error starts here.
  2. Adding GST to an exclusive amount: multiply by 1.15. The extra 0.15 is the GST.
  3. Removing GST from an inclusive total: divide by 1.15 to get the exclusive price.
  4. The GST already inside an inclusive total is 15/115 of it, which simplifies to 3/23 — so total ÷ 23 × 3.
  5. Round to the nearest cent once, at the end. Rounding mid-calculation is what leaves an invoice a cent out.
RATE     15%   standard rate, New Zealand, since 1 Oct 2010 (IRD)
ADD      exclusive × 1.15        = inclusive
REMOVE   inclusive ÷ 1.15        = exclusive
PORTION  inclusive ÷ 23 × 3      = GST        (15/115 = 3/23)
CHECK    1,000.00 × 1.15 = 1,150.00   ·   1,150.00 ÷ 23 × 3 = 150.00

SOURCE·IRD — GST rate 15% since 1 Oct 2010·REVIEWED JUL 2026

The worked examples, in full →

How to work out GST in your head

There are only two calculations, and they are not symmetrical — which is where nearly every GST mistake comes from.

× 1.15

Adding GST. Your price is GST-exclusive and you want the total. $200 × 1.15 = $230. The GST itself is $30.

÷ 23 × 3

Finding the GST inside a price. The total already includes GST. $230 ÷ 23 × 3 = $30. This is the one worth memorising.

÷ 1.15

Stripping GST out. Gives the GST-exclusive price. $230 ÷ 1.15 = $200. Same job as above, different output.

The mistake that costs real money

If a client agreed to pay you $1,150 including GST, the GST is not 15% of $1,150. Fifteen percent of $1,150 is $172.50, but the correct GST is $150 — because the GST-exclusive price was $1,000. Taking 15% of an inclusive figure overstates the GST by 15% every single time.

It matters in both directions. Overstate the GST and you hand Inland Revenue money that was your income. Understate it and you have a shortfall to make up at return time out of money you have already spent.

GST at a glance

Left three columns treat the amount as GST-exclusive. Right two treat the same figure as a GST-inclusive total.

NZ · 15% · JUL 2026

Amount+ GSTTotalGST insideEx GST
$100.00$15.00$115.00$13.04$86.96
$250.00$37.50$287.50$32.61$217.39
$500.00$75.00$575.00$65.22$434.78
$1,000.00$150.00$1,150.00$130.43$869.57
$2,500.00$375.00$2,875.00$326.09$2,173.91
$5,000.00$750.00$5,750.00$652.17$4,347.83

SOURCE·IRD — GST rate 15% since 1 Oct 2010·REVIEWED JUL 2026

Do you need to register for GST?

In New Zealand, registration becomes compulsory once your turnover passes $60,000 in any twelve-month period. That test looks backwards over the last twelve months and forwards over the next twelve, so a single large contract that will clearly push you over the line triggers it even before the money arrives.

Below the threshold it is a genuine choice, and the right answer depends entirely on who your customers are:

  • Selling to GST-registered businesses? Register. They claim the GST back, so your price does not effectively change for them, and you get to claim GST on your own costs.
  • Selling to consumers? Usually do not. Registering means either raising your price 15% or absorbing it — and consumers cannot claim anything back.
  • Large startup costs? Registering early lets you claim the GST on equipment and setup, which can be worth thousands in year one.
Once registered, you must charge GST on every taxable supply — you cannot pick and choose per customer. You also have to file returns, usually every two or six months. If that admin is the thing stopping you, an accounting package or a service like Hnry handles the filing automatically.

If the filing is the part that stops you

The arithmetic above is free forever. Returns are the bit people actually pay to be rid of.

Never file a GST return again

Hnry takes your income, works out the GST, ACC and income tax, pays them and files the returns. Built for NZ sole traders.

See Hnry →

GST questions, answered

How do I calculate 15% GST in New Zealand?
To add GST, multiply the GST-exclusive price by 0.15 and add it on — or simply multiply by 1.15. To go the other way and find the GST inside a price that already includes it, divide the total by 1.15. The GST portion of a GST-inclusive price is the total divided by 23, then multiplied by 3.
What is the divide by 23 multiply by 3 rule?
It is the fastest way to find the GST already contained in a GST-inclusive price. Because 15% GST means the total is 115% of the original, and 15/115 simplifies to 3/23, the GST component of any inclusive amount is the total ÷ 23 × 3. On a $115 invoice that is 115 ÷ 23 × 3 = $15.
Is GST 15% on everything in New Zealand?
Almost. The standard rate of 15% applies to most goods and services. A small number of supplies are zero-rated (exports, and land sold between GST-registered parties) or exempt (residential rent, most financial services, donated goods sold by non-profits). If a supply is exempt you charge no GST and cannot claim GST on related costs.
When do I have to register for GST?
Registration is compulsory in New Zealand once your turnover exceeds $60,000 in any twelve-month period, looking both backwards over the last 12 months and forwards over the next 12. Below that threshold registering is optional — worth it if your customers are GST-registered businesses who claim it back, usually not worth it if you sell to consumers.
Why does adding then removing GST not return the same number?
It does, as long as you do not round in the middle. Rounding the GST amount to the nearest cent at each step can leave you a cent out on large figures. Inland Revenue accepts rounding to the nearest cent on the final figures, so a one-cent difference on a big invoice is not a problem.
What GST rate does Australia use?
Australia's GST is 10%, so you multiply by 1.1 to add it and divide by 11 to find the GST inside a GST-inclusive price. Switch the calculator to AU and the maths follows automatically.
Does the calculator store what I type?
Only in your own browser, so the amount and rate are still there next time you visit. Nothing is sent to a server — there is no account and no tracking of the figures you enter.

GST on common amounts

GST on $10GST on $20GST on $25GST on $30GST on $40GST on $50GST on $60GST on $75GST on $80GST on $100GST on $120GST on $150GST on $200GST on $250GST on $300GST on $400GST on $500GST on $600GST on $750GST on $800GST on $1,000GST on $1,200GST on $1,500GST on $2,000GST on $2,500GST on $3,000GST on $5,000GST on $10,000

Working in Australia instead? The 10% Australian GST calculator runs the same maths at the ATO rate.

Where these figures come from

Every number this tool uses, with the official source and the date it applies from. If a figure here is out of date, the source link is the one to trust.

Ranked by what a business actually reaches for next — not alphabetically. Figures carry across; nothing needs retyping.

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