Add or remove GST and see the net, tax and gross amounts.
Calculated locally in your browser.
How do you calculate GST on a price?
To add GST: GST = Amount × Rate ÷ 100, then Gross = Amount + GST. To remove GST from a tax-inclusive price: Net = Amount ÷ (1 + Rate ÷ 100), then GST = Amount − Net. Use "Add" when your price excludes tax and "Remove" when it already includes it. Adding 18% to 1,000 gives 180 tax and a 1,180 total.
Understanding your result
Use “Add” when your price excludes tax, and “Remove” when the price already includes GST and you need the tax component.
Formula and method
Add: GST = Amount × Rate ÷ 100; Gross = Amount + GST. Remove: Net = Amount ÷ (1 + Rate ÷ 100); GST = Amount − Net.
Assumptions and limitations
Results are estimates for general guidance only and not financial or tax advice. You must supply the correct GST rate, as this tool does not know local rates or which goods are exempt or zero-rated. Actual tax owed depends on your registration status, jurisdiction and current rules, so confirm with a qualified professional.
Worked example
Adding 18% GST to 1,000 gives 180 tax and a 1,180 total. Removing 18% from 1,180 returns the 1,000 net.
How to use this tool
- Enter the amount.
- Set the GST rate.
- Choose Add GST or Remove GST.
- Press Calculate.
Common mistakes to avoid
- Using “Add” on a price that already includes GST.
About the GST Calculator
Add Goods and Services Tax to a net price, or extract the GST already included in a gross price.
Who should use this tool
Small business owners, freelancers, invoicing staff and shoppers in countries that use Goods and Services Tax who need to add GST to a net price or pull the tax out of a gross figure. Useful when preparing quotes, checking receipts, or reconciling the tax portion of a payment.
Benefits
- Adds or removes GST at whatever rate you enter
- Shows net, tax and gross amounts together clearly
- Speeds up quoting and receipt checking
- Keeps figures private in your browser, no sign-up
Practical use cases
- Adding GST to a quote or invoice line
- Extracting the tax already inside a gross price
- Checking the GST shown on a supplier receipt
- Working back to a net price for bookkeeping
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Frequently asked questions
What GST rate should I use?
Rates vary by country and product. Enter the rate that applies in your jurisdiction.
Why can't I just take a percentage off the gross price?
Because GST was added to the smaller net amount, not the gross. Taking the rate off the total over-removes the tax. The tool divides the gross by one plus the rate, matching the example where removing 18% from 1,180 correctly returns 1,000 net, not 1,180 minus 18%.
Does the tool decide which items are taxable?
No. It applies whatever rate you enter to the amount you provide and does not judge whether an item is standard-rated, zero-rated or exempt. You decide the correct rate for each item based on the rules in your country before entering it here.