GST Calculator
Add or remove GST instantly for Australia, India, New Zealand, Canada, Singapore and more. Get the net amount, GST component, and gross total in one click.
Choose your country (or enter a custom rate), then add GST to a net price or remove GST from a gross price. The calculator breaks down the exact GST amount and the before/after totals.
What is a GST Calculator?
A GST calculator works out the Goods and Services Tax on any price โ either adding GST to a net (tax-exclusive) amount or removing GST from a gross (tax-inclusive) amount. GST is a value-added consumption tax applied to most goods and services in many countries including Australia, India, New Zealand, Canada, and Singapore. This calculator handles all of them, plus any custom rate you enter.
Whether you're a business owner preparing an invoice, a freelancer quoting a client, a shopper checking a price, or an accountant reconciling figures, a GST calculator removes the mental maths and gives you the exact net amount, GST component, and gross total instantly.
How to Calculate GST
The maths depends on whether you're adding or removing GST. Adding GST is straightforward multiplication; removing GST requires dividing by one plus the rate, because the GST is already baked into the gross price.
GST Amount = Net ร (Rate รท 100)
Gross = Net + GST Amount
REMOVE GST (gross โ net):
Net = Gross รท (1 + Rate รท 100)
GST Amount = Gross โ Net
Example (Australia, 10%):
Add: $1,000 net โ $100 GST โ $1,100 gross
Remove: $1,100 gross โ $100 GST โ $1,000 net
How to Use This GST Calculator
Select "Add GST" if you have a price before tax and want to know the total, or "Remove GST" if you have a tax-inclusive total and want to find the GST component and the pre-tax amount. Choose your country from the dropdown (or pick "Custom rate" to enter your own), enter the amount, and click Calculate. You'll instantly see the net, the GST component, and the gross.
GST Rates by Country
GST rates vary significantly around the world. Here are the standard rates used in this calculator:
| Country | GST Rate | Notes |
|---|---|---|
| Australia | 10% | Flat rate on most goods and services since 2000 |
| New Zealand | 15% | One of the broadest, simplest GST systems |
| Singapore | 9% | Increased to 9% in 2024 |
| Canada | 5% | Federal GST; provinces may add PST/HST on top |
| India | 5% / 12% / 18% / 28% | Multiple slabs depending on the goods or service |
What is GST?
GST (Goods and Services Tax) is an indirect, value-added tax levied on the supply of goods and services. It's collected by businesses on behalf of the government at each stage of the supply chain, but ultimately paid by the end consumer. Businesses registered for GST charge it on their sales (output tax) and can usually claim back the GST they pay on business purchases (input tax credits), remitting only the difference to the tax authority.
Adding GST vs Removing GST
Adding GST is what you do when pricing a product or service โ you have your base price and need to add tax to reach the final customer price. Removing GST (also called back-calculating or extracting GST) is what you do when you have a tax-inclusive total and need to find the GST portion โ essential for accounting, claiming input tax credits, and completing tax returns. A common mistake is simply taking 10% off a gross figure to "remove" GST; the correct method is to divide by 1.1, because the GST was calculated on the smaller net amount, not the gross.
GST for Small Businesses and Freelancers
If you run a business or freelance, a GST calculator is part of your daily toolkit. You'll use it to add GST when quoting and invoicing clients, to remove GST when recording expenses and claiming input tax credits, and to reconcile your GST liability at tax time. In most countries you must register for GST once your turnover exceeds a threshold (for example, A$75,000 in Australia), after which you're required to charge GST on your sales.
GST for Shoppers
As a consumer, GST is usually already included in the displayed price in countries like Australia and New Zealand, so the price you see is the price you pay. This calculator helps you understand how much of a price is actually tax โ useful for budgeting, comparing tax-inclusive and tax-exclusive quotes, or working out the GST you could claim back on eligible purchases (for example, tourist refund schemes that refund GST on goods taken out of the country).
Common GST Mistakes to Avoid
- Removing GST by subtracting the rate. Taking 10% off a gross price is wrong โ you must divide by 1.1, or you'll understate the net amount.
- Using the wrong slab (India). India's rate depends on the product category โ applying 18% to a 5% item overstates the tax.
- Forgetting GST-free items. Many essentials (basic food, some health and education services) are GST-free or exempt โ don't add GST where it doesn't apply.
- Mixing up Canada's GST and HST. Canada's federal GST is 5%, but many provinces add PST or combine into HST โ the total can be much higher than 5%.
- Rounding too early. Round only the final figures, not intermediate steps, to avoid small discrepancies on invoices.
Frequently Asked Questions
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