GST Calculator: Add or Remove GST
This GST calculator adds GST to a price or works backwards from a GST-inclusive amount to find the base price and the tax. For India it splits the tax into CGST and SGST for sales within a state, or IGST for sales between states, at the current 5%, 18% and 40% rates. Presets cover Australia, New Zealand, Singapore and Canada, and a custom rate handles any VAT or sales tax.
Use it for invoices, checking a bill, or pricing a product so the customer sees a round number after tax.
GST formulas
Add GST: GST = Net price × Rate ÷ 100, then Gross = Net + GST
Remove GST: Net = Gross ÷ (1 + Rate ÷ 100), then GST = Gross − Net
Removing GST is not the same as subtracting the percentage. An 18% GST on ₹1,000 gives ₹1,180, but 18% of ₹1,180 is ₹212, not ₹180. Dividing by 1.18 recovers the correct base price.
In India, GST on a sale within a state is split equally: CGST (central) and SGST (state) at half the rate each. A sale between states is charged as IGST at the full rate. The total tax is the same either way.
Worked example
A product priced at ₹1,000 before tax, 18% GST, sold within the same state:
| GST (18%) | ₹180 |
|---|---|
| CGST (9%) | ₹90 |
| SGST (9%) | ₹90 |
| Price including GST | ₹1,180 |
Reverse: a restaurant bill of ₹1,180 including 18% GST has a base of ₹1,180 ÷ 1.18 = ₹1,000 and GST of ₹180.
Current GST rates
India moved to a simpler structure from 22 September 2025: 5% for essentials and most goods, 18% as the standard rate, and 40% for luxury and sin goods such as tobacco and high-end cars. The older 12% and 28% slabs were largely folded into 5% and 18% and are kept here for older invoices. Gold and jewellery stay at 3%.
Australia charges 10% GST with fresh food, most health and education exempt. New Zealand charges 15% on almost everything. Singapore raised GST to 9% in 2024. Canada charges 5% federal GST, with provinces adding PST or combining into HST of 13% to 15%. For a Canadian province, use the custom rate with the combined percentage.
Frequently asked questions
How do I calculate GST on an amount?
Multiply the amount by the rate and divide by 100. GST at 18% on ₹2,500 is ₹2,500 × 18 ÷ 100 = ₹450, so the price including GST is ₹2,950. Within a state, that ₹450 is ₹225 CGST plus ₹225 SGST.
How do I remove GST from a total?
Divide the total by (1 + rate ÷ 100). For ₹2,950 at 18%: ₹2,950 ÷ 1.18 = ₹2,500 base price, and GST is ₹450. Choose "Remove GST" above and the calculator does this for you.
What is the difference between CGST, SGST and IGST?
CGST goes to the central government and SGST to the state, each at half the GST rate, for supplies within one state. IGST is charged at the full rate on supplies between states and on imports, and is later shared between centre and state. The buyer pays the same total.
What are the GST rates in India now?
Since 22 September 2025 the main slabs are 5% and 18%, with a 40% rate for luxury and sin goods. Some items are exempt (0%), gold is 3% and rough diamonds 0.25%. The old 12% and 28% slabs mostly no longer apply but are available for older invoices.
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Last updated . Formulas are shown on the page and checked against the worked example.
This calculator is for general information and education only. It is not professional advice. Confirm important decisions with a qualified adviser.