Calculator

GST and BAS calculator

Add or take out GST exactly to the cent, estimate the GST for a BAS period from your totals, and check the dates of each reporting period. Everything is worked out in your browser; nothing you type is sent anywhere.

Add or remove GST Estimate a BAS period

Step one

Add or remove GST

GST in Australia is 10% of the GST-exclusive price, which makes it one eleventh of a GST-inclusive price.

Adding GST: GST = price × 10%; $200.00 + $20.00 = $220.00
Removing GST: GST = price ÷ 11; $220.00 − $20.00 = $200.00

The calculator works in whole cents and rounds GST to the nearest cent, with half a cent rounded up, so the excluding-GST amount and the GST always add back to exactly the including-GST amount.

Add or remove GST

The amount I have is

Excluding GSTadd 10%Including GSTtake out 1/11

Amount

Excluding GST: $1,000.00
GST (10%): $100.00
Including GST: $1,100.00

Step two

Estimate a BAS period

Follows the shape of the ATO’s GST calculation worksheet, in simplified form. Use it to sense-check a period, not to complete your BAS.

Estimate a BAS period’s GST

Enter the period’s totals, including GST, and see GST on sales (1A), GST on purchases (1B) and the difference.

Sales

G1 Total sales

All sales for the period, including any GST

G2 Export sales

Included in G1

G3 Other GST-free sales

Included in G1

G4 Input-taxed sales

Included in G1, for example residential rent

Purchases

G10 Capital purchases

Including any GST

G11 Non-capital purchases

Including any GST

G14 Purchases with no GST in the price

Included in G10 and G11

1A GST on sales

$2,800.00

1/11 of $30,800.00 taxable sales

1B GST on purchases

$1,100.00

1/11 of $12,100.00 purchases with GST

Estimated GST payable

$1,700.00

1A less 1B

Reporting periods in a financial year

Financial year

You report

Q1: July to September
1 July 2026 to 30 September 2026
Q2: October to December
1 October 2026 to 31 December 2026
Q3: January to March
1 January 2027 to 31 March 2027
Q4: April to June
1 April 2027 to 30 June 2027

Lodgement due dates depend on how you lodge and whether you use a registered agent. Check yours in ATO online services or with your agent.

What this estimate leaves out

It assumes every sale and purchase you enter has the GST treatment its label describes, and it leaves out adjustments, purchases for making input-taxed sales, private use, fuel tax credits, PAYG and other BAS labels. The BAS itself is completed in whole dollars; follow the ATO’s instructions for cents. Your registered tax or BAS agent, or the ATO, can tell you how the rules apply to you.

In Kumry

From totals you type to figures you can trace

In Kumry, the GST code sits on each invoice and bill line, so the period’s GST summary is prepared from the transactions themselves, and each amount opens to the transactions behind it. You, or your registered agent, review and lodge with the ATO.

See how it works What bookkeeping costs you today

Why does removing GST divide by 11?

A GST-inclusive price is 110% of the GST-exclusive price, and the GST is 10 of those 110 parts: one eleventh.

Is anything I type stored or sent?

No. The calculations run in your browser, and the page does not save or send what you enter.

Are my sales GST-free?

That depends on what you sell and the conditions in the GST law. Ask your tax adviser or check with the ATO.

Can I use this to lodge my BAS?

No. It is an estimate to help you sense-check figures. Lodge through ATO online services or your registered agent.

Let the GST work itself out as you go

Request access, or book a walkthrough of GST and BAS preparation in Kumry.

Get started Book a walkthrough

Kumry accounts are set up on request: Get started takes you to a short request form.

Calculator

GST and BAS calculator

Add or remove GST Estimate a BAS period

Step one

Add or remove GST

GST in Australia is 10% of the GST-exclusive price, which makes it one eleventh of a GST-inclusive price.

Adding GST: GST = price × 10%; $200.00 + $20.00 = $220.00
Removing GST: GST = price ÷ 11; $220.00 − $20.00 = $200.00

The calculator works in whole cents and rounds GST to the nearest cent, with half a cent rounded up, so the excluding-GST amount and the GST always add back to exactly the including-GST amount.

Add or remove GST

The amount I have is

Excluding GSTadd 10%Including GSTtake out 1/11

Amount

Excluding GST: $1,000.00
GST (10%): $100.00
Including GST: $1,100.00

Step two

Estimate a BAS period

Follows the shape of the ATO’s GST calculation worksheet, in simplified form. Use it to sense-check a period, not to complete your BAS.

Estimate a BAS period’s GST

Enter the period’s totals, including GST, and see GST on sales (1A), GST on purchases (1B) and the difference.

Sales

G1 Total sales

All sales for the period, including any GST

G2 Export sales

Included in G1

G3 Other GST-free sales

Included in G1

G4 Input-taxed sales

Included in G1, for example residential rent

Purchases

G10 Capital purchases

Including any GST

G11 Non-capital purchases

Including any GST

G14 Purchases with no GST in the price

Included in G10 and G11

1A GST on sales

$2,800.00

1/11 of $30,800.00 taxable sales

1B GST on purchases

$1,100.00

1/11 of $12,100.00 purchases with GST

Estimated GST payable

$1,700.00

1A less 1B

Reporting periods in a financial year

Financial year

You report

Q1: July to September
1 July 2026 to 30 September 2026
Q2: October to December
1 October 2026 to 31 December 2026
Q3: January to March
1 January 2027 to 31 March 2027
Q4: April to June
1 April 2027 to 30 June 2027

Lodgement due dates depend on how you lodge and whether you use a registered agent. Check yours in ATO online services or with your agent.

What this estimate leaves out

In Kumry

From totals you type to figures you can trace

See how it works What bookkeeping costs you today

Why does removing GST divide by 11?

A GST-inclusive price is 110% of the GST-exclusive price, and the GST is 10 of those 110 parts: one eleventh.

Is anything I type stored or sent?

No. The calculations run in your browser, and the page does not save or send what you enter.

Are my sales GST-free?

That depends on what you sell and the conditions in the GST law. Ask your tax adviser or check with the ATO.

Can I use this to lodge my BAS?

No. It is an estimate to help you sense-check figures. Lodge through ATO online services or your registered agent.

Let the GST work itself out as you go

Request access, or book a walkthrough of GST and BAS preparation in Kumry.

Get started Book a walkthrough

Kumry accounts are set up on request: Get started takes you to a short request form.