Free GST Calculator
Free Australian GST calculator. Enter a price, choose add or remove, and get the exact GST amount, ex-GST price, and inc-GST total. No signup needed.
Free online tool
Works for adding 10% GST to a price, or stripping GST out of an inc-GST total. Both directions, instantly.
Getting GST wrong costs Australian tradies time, ATO penalties, and client trust. This free calculator handles both directions instantly — enter any amount to see the ex-GST price, GST component, and inc-GST total.
Enter an amount above to see your GST calculation
Don't want to type all this?
SMASH does this automatically from a 30-second voice description. No form, no typing, no GST maths.
Try SMASH FreeHow to use
Enter your amount
Type in the dollar amount you want to calculate GST on. Use any dollar value — the calculator works in both directions.
Choose Add or Remove GST
Select Add GST if you have an ex-GST price and want to know what to charge the client. Select Remove GST if you've been given an inc-GST price and need to see the breakdown.
Read your result — or email it to yourself
Your ex-GST amount, GST component, and inc-GST total appear instantly. Tap Email to save the calculation for your records or share with your bookkeeper.
10%
Australian GST rate
$75k
GST registration threshold
4.9★
App Store rating
How it works
Price × 1.1
$500 × 1.1 = $550
Multiply your ex-GST price by 1.1 to get the total your customer pays. The $50 difference is the GST you collect and remit to the ATO.
Price ÷ 1.1
$550 ÷ 1.1 = $500
Divide an inc-GST price by 1.1 to find the ex-GST amount. To find just the GST component: price ÷ 11.
Compare invoicing options
From tradies using SMASH
"I was always second-guessing my GST. SMASH just handles it automatically on every invoice."
Mark T.
Electrician, Perth
"ATO audit-ready invoices without thinking about GST at all. That's worth the subscription alone."
Sandra K.
Bookkeeper, Brisbane
"Before SMASH I'd Google GST every single job. Now the app calculates it and adds it to the invoice in one go."
Pete R.
Plumber, Sydney
From the blog
FAQ
SMASH adds GST to every invoice automatically — correct every time, ATO-compliant, your ABN on every page.