GST Calculator
Enter an amount and a GST rate, choose whether GST is added or already included, and see the base amount, the tax, and the total in your own number format.
Overview
Goods and services tax (GST) is charged in many countries, including Australia, Canada, New Zealand, Singapore, and India. It can be worked out two ways depending on the number you start from: adding GST on top of a base price to get the amount to charge, or working backward from a GST-inclusive price to find the base price and the tax inside it. This calculator handles both directions from the same form.
For India, where GST within a state is split between central and state tax, you can show the tax as CGST and SGST/UTGST for a sale within a state, or as IGST for a sale between states. Amounts are shown in your region's number format, or you can choose international or Indian digit grouping.
Examples & Sample Data
Add 10% GST to a price in Australia
Amount: 1250, Rate: 10, Mode: Add GST, Breakdown: Single GST amount
Base amount: 1,250.00 GST (10%): 125.00 Total amount: 1,375.00
Remove 15% GST from a New Zealand price
Amount: 230, Rate: 15, Mode: Remove GST, Breakdown: Single GST amount
Base amount: 200.00 GST (15%): 30.00 Total amount: 230.00
Add 18% GST within an Indian state
Amount: 125000, Rate: 18, Mode: Add GST, Breakdown: India, within a state, Format: Indian
Base amount: 1,25,000.00 CGST (9%): 11,250.00 SGST/UTGST (9%): 11,250.00 GST (18%): 22,500.00 Total amount: 1,47,500.00
How It Works
- Enter the amount, then type a GST rate or tap one of the common rates.
- Choose "Add GST" if your amount excludes tax, or "Remove GST" if it already includes tax.
- For Indian GST, optionally choose the CGST + SGST or IGST breakdown.
- Read the base amount, the tax, and the total. Results update as you type.
Frequently Asked Questions
No. Every calculation runs locally in your browser.
Base amount = Total ÷ (1 + rate/100). The GST is the difference between the total and the base amount. Multiplying the total by the rate would overstate the tax.
Use the rate that applies to your country and item. Standard rates are 5% in Canada (plus provincial tax in some provinces), 9% in Singapore, 10% in Australia, and 15% in New Zealand. In India, most goods and services are taxed at 5% or 18% since 22 September 2025, with 40% on select luxury and sin goods and 3% on gold and silver. The calculator accepts any rate.
For a sale within one Indian state or union territory, the GST rate is split equally into CGST (central) and SGST or UTGST (state). For a sale from one state to another, or an import, the full rate is charged as IGST.
When the total tax has an odd number of paise, it can't be halved exactly. The calculator rounds CGST and gives SGST the remainder, so the two always add up to the total GST.
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