# GST calculator (add or remove GST) 2026-27

Source: https://calculatax.com/gst/gst-calculator/
Title: GST Calculator Australia: Add or Remove 10% GST | Calculatax
Last updated: 2026-11-06

This GST calculator adds 10% GST to a price or finds the GST inside a GST-inclusive total, using the 2026-27 rate from the [ATO's goods and services tax page](https://www.ato.gov.au/businesses-and-organisations/preparing-lodging-and-paying/business-activity-statements-bas/goods-and-services-tax-gst). A $1,320 total includes **$120** of GST. A $480 price becomes $528 with GST.

The calculator covers the arithmetic only. Registration, GST-free items and BAS reporting are set out under [GST in Australia](https://calculatax.com/gst/). This is one of our [Australian tax & pay calculators](https://calculatax.com/).

| Default example | Mode | Price excluding GST | GST | Price including GST |
|---|---|---|---|---|
| $1,320 | Remove GST (÷ 11) | $1,200.00 | $120.00 | $1,320.00 |
| $480 | Add GST (× 1.1) | $480.00 | $48.00 | $528.00 |

*Default results at the 10% GST rate, 2026-27. Source: ATO.*

## Adding GST: multiply by 1.1

To add GST, multiply the price before GST by 1.1. The GST itself is the price × 0.1.

Say a printer quotes $480 for a run of flyers, before GST. The GST is $480 × 0.1 = $48, and the price including GST is $480 × 1.1 = $528.

The reverse step doesn't work by taking 10% off. Removing 10% from $528 gives $475.20, which is $4.80 short of the original $480. GST is added to the smaller, pre-GST amount, so it has to come off the larger total with a different divisor.

Businesses setting a round shelf price work the other way, starting from the total. Pricing at $250 plus GST would give a $275 shelf price, which is $25 more for the customer.

**Selling at $250 including GST**

| Step | Working | Amount |
|---|---|---|
| Price before GST |  | +$227.27 |
| GST |  | +$22.73 |
| **Shelf price** |  | **$250** |

## Removing GST: divide by 11, not 10%

To find the GST in a GST-inclusive price, divide the total by 11. To find the price before GST, divide the total by 1.1, or subtract the GST from the total.

Say an electrician's invoice totals $1,320 including GST. The GST is $1,320 ÷ 11 = $120, and the price before GST is $1,320 ÷ 1.1 = $1,200. To check it, $1,200 × 10% = $120, and $1,200 + $120 = $1,320.

A common GST mistake is taking 10% of the total. It gives $132, which is $12 too much. That $132 is 11% of the $1,200 pre-GST price, not 10%.

| Method on a $1,320 GST-inclusive total | GST result | Price before GST | Correct? |
|---|---|---|---|
| Divide by 11 | $120.00 | $1,200.00 | Yes |
| Take 10% of the total | $132.00 | $1,188.00 | No, overstates GST by $12 |

*Removing GST from a GST-inclusive total at the 10% rate, 2026-27. Source: ATO rate; Calculatax calculation.*

The error is always one-hundred-and-tenth of the total, so it grows with the invoice size: $12 on $1,320 and $50 on a $5,500 total.

## Reverse GST from a total on a receipt

Most receipts show a GST-inclusive total, so use the remove GST mode and enter that total. Many receipts also print the GST amount, which you can use to check the result.

Mixed receipts need more care. A supermarket receipt often combines GST-free food with taxable items such as cleaning products, so dividing the whole total by 11 overstates the GST. Say a $77 receipt has $55 of GST-free groceries and $22 of taxable household items.

| $77 receipt | Taxable part only | The whole total |
|---|---|---|
| Amount you divide by 11 | $22 | $77 |
| GST result | $2 | $7 |

*Dividing the full total makes the GST $5 too high.*

Enter only the taxable part, which many receipts mark with a symbol next to each item.

### Business buyers and GST credits

The same applies to a business claiming GST credits. The credit is the GST actually included in the purchase, so a GST-free line on a mixed invoice adds nothing to it. Over a quarter, those credits are totalled at label 1B of the BAS and set against the GST collected on sales at label 1A.

A business that isn't registered for GST can't charge it. If its receipt shows no GST, the total contains no GST to remove, and a business buyer has no credit to claim.

## Common prices with and without GST

The table shows each price two ways. The first set treats it as a price before GST and adds 10%. The second treats it as a GST-inclusive total and takes out one-eleventh.

| Price | GST to add (price excludes GST) | Total with GST | GST inside (price includes GST) | Price without GST |
|---|---|---|---|---|
| $10 | $1.00 | $11.00 | $0.91 | $9.09 |
| $50 | $5.00 | $55.00 | $4.55 | $45.45 |
| $99 | $9.90 | $108.90 | $9.00 | $90.00 |
| $250 | $25.00 | $275.00 | $22.73 | $227.27 |
| $1,000 | $100.00 | $1,100.00 | $90.91 | $909.09 |
| $5,000 | $500.00 | $5,500.00 | $454.55 | $4,545.45 |

*Common prices at the 10% GST rate, 2026-27, rounded to the cent. Source: ATO rate; Calculatax calculation.*

A $99 price includes exactly $9.00 of GST, so it's $90.00 before GST. And $1,000 including GST carries $90.91 of GST, not $100.

## GST is the same in every state

GST is a federal tax at 10% across Australia. The rate is identical in New South Wales, Victoria, Queensland, Western Australia, South Australia, Tasmania, the ACT and the Northern Territory.

There's no extra state sales tax on top of GST, unlike sales taxes in some other countries. A Victorian or Queensland price uses the same formula as any other state.

### Interstate sales, state taxes and New Zealand

Sales across state lines are no different: a Perth business selling $480 of stock to a Hobart customer charges $48 of GST, the same as for a buyer next door. State taxes such as stamp duty and payroll tax are separate and don't change the GST.

New Zealand also has a GST, but at a different rate. The figures here apply to Australian prices only.

## When the 10% formula does not apply

The calculator assumes the whole amount is a taxable sale at 10%. The real GST will differ in these cases:

- GST-free items, such as most basic food, carry no GST at all.
- Input-taxed items, such as residential rent and bank fees, also carry no GST.
- A seller that isn't registered for GST doesn't charge it, so there's nothing to remove.
- Mixed invoices need the taxable part separated first, as in the receipt example above.
- Property sold under the margin scheme works out GST on the margin, not the full price.
- Imported goods and overseas digital services follow their own collection rules.

GST applies to the price actually charged. If a $250 pre-GST item is discounted by 20% to $200, the GST is $20 and the total is $220.

On invoices with many lines, rounding the GST on each line and rounding it on the total can differ by a cent or two. The calculator rounds every result to the nearest cent.

The calculator also doesn't decide whether you must register for GST or how to report it. The [ATO's rules on registering for GST](https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/registering-for-gst) set out who must register. For whether a sale is taxable, check the ATO rules or ask a registered tax agent or BAS agent. GST is also separate from the income tax on a business's profit, which is covered in the [tax return guide](https://calculatax.com/tax-return/).

## GST calculation questions: adding GST, removing it and the 9.09% share

### How do you calculate GST?

On a price that doesn't yet include it, multiply the price by 0.1, or multiply by 1.1 to get the total. A $480 price carries $48 of GST and becomes $528. The rate is 10% everywhere in Australia. If the price already includes GST, divide by 11 instead of taking 10%.

### How do you calculate goods and services tax from a total that includes it?

Divide the total by 11 to get the goods and services tax. A $1,320 total contains $120 of GST, and the price before GST is $1,200. Taking 10% of the total gives $132, which overstates the GST by $12. For the pre-GST price, divide the total by 1.1 or subtract the GST.

### How much GST is in $100?

A $100 price that includes GST contains $9.09 of GST, so the price before GST is $90.91. If $100 is the price before GST, the GST is $10.00 and the total is $110.00. Check which way a price is quoted, because the two answers differ by 91 cents.

### What percentage of a GST-inclusive price is GST?

GST is about 9.09% of a GST-inclusive price, which is one-eleventh. The rate is still 10%, but it's charged on the smaller pre-GST price. On a $5,000 total, the GST is $454.55 rather than $500. That gap is why dividing by 11 gives the right answer and taking 10% doesn't.

- [BAS calculator](https://calculatax.com/gst/bas-calculator/): turn a quarter's sales and purchases into GST payable or refundable.

*Estimates only, based on published rates for 2026-27. General information, not tax or financial advice.*

## Sources

- [ATO: Goods and services tax (GST)](https://www.ato.gov.au/businesses-and-organisations/preparing-lodging-and-paying/business-activity-statements-bas/goods-and-services-tax-gst)
- [ATO: Registering for GST](https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/registering-for-gst)