GST Calculator: Add or Remove GST
Add GST to a price, remove GST from a GST-inclusive price, or find the GST rate. Works for India, Pakistan, Australia, New Zealand, Canada and Singapore, with every step shown and CGST and SGST for India.
For information only. GST rates and rules change. Check your tax authority before you file or invoice. Not tax advice.
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How to calculate GST
GST is a percentage added on the net price (the price before tax). Two formulas cover almost every case.
- Add GST: GST = net × rate ÷ 100. Gross = net + GST.
- Remove GST: Net = gross ÷ (1 + rate ÷ 100). GST = gross − net.
- Find the rate: Rate = (gross − net) ÷ net × 100.
Quick shortcut for 18% GST: multiply the net price by 1.18 to get the gross, and divide the gross by 1.18 to get the net. For 10% (Australia) use 1.10, for 15% (New Zealand) use 1.15, for 9% (Singapore) use 1.09.
Reverse GST calculator: if the price already includes GST, choose Remove GST. This is the reverse calculation: net = gross ÷ (1 + rate ÷ 100). You get the price before GST, the GST amount and, for India, the CGST and SGST split.
GST rates by country
| Country | Standard GST rate | Notes |
|---|---|---|
| India | 5%, 18%, 40% (plus 0% and 3%) | Rate depends on the item. Check the GST rate finder for your HSN code. |
| Pakistan | 18% | Federal sales tax (General Sales Tax) collected by FBR. Provinces charge their own sales tax on services. |
| Australia | 10% | Some food, health and education items are GST-free. |
| New Zealand | 15% | Applies to most goods and services. |
| Canada | 5% federal GST | HST of 13% to 15% applies in Ontario and the Atlantic provinces. Quebec and some provinces also add a separate provincial tax. |
| Singapore | 9% | Since 1 January 2024. |
Use the Other / custom option for any other rate. Countries such as the UK and Ireland call it VAT, and the US uses sales tax, which is a different calculation.
India: GST slabs, CGST, SGST and IGST
Since the September 2025 reform, most goods and services fall in the 5% and 18% slabs, with 40% for a short list of sin and luxury items. Gold and silver carry 3%. Some items stay at 0%.
- CGST + SGST: for a sale inside one state, the GST splits into two equal halves. At 18%, that is 9% CGST and 9% SGST.
- IGST: for a sale between states, the full 18% is charged as IGST.
The total tax is the same. Only the split changes. This calculator shows the halves for India so your invoice lines match.
Worked examples
1. Add 18% GST to ₹10,000. GST = 10,000 × 18 ÷ 100 = ₹1,800. Total = ₹11,800.
2. Remove 18% GST from ₹11,800. Net = 11,800 ÷ 1.18 = ₹10,000. GST = ₹1,800.
3. GST on MRP. The MRP already includes GST. For an MRP of ₹590 at 18%, net = 590 ÷ 1.18 = ₹500 and GST = ₹90.
4. Australia, 10%. A$550 including GST. Net = 550 ÷ 1.10 = A$500. GST = A$50.
5. Find the rate. Net 2,000 and gross 2,100. Rate = 100 ÷ 2,000 × 100 = 5%.
GST calculation formula: inclusive and exclusive
A GST-exclusive price is the price before GST. A GST-inclusive price already has GST in it. This free GST calculator handles both.
- GST exclusive (add GST): GST amount = original price × GST% ÷ 100. Final price = original price + GST amount.
- GST inclusive (remove GST): Original price = final price × 100 ÷ (100 + GST%). GST amount = final price − original price.
The GST percentage is simply the GST amount divided by the original price, times 100.
18% GST and 5% GST on common amounts
| Price before GST | GST rate | GST amount | Price with GST |
|---|---|---|---|
| ₹100 | 18% | ₹18 | ₹118 |
| ₹500 | 18% | ₹90 | ₹590 |
| ₹1,000 | 18% | ₹180 | ₹1,180 |
| ₹10,000 | 18% | ₹1,800 | ₹11,800 |
| ₹1,000 | 5% | ₹50 | ₹1,050 |
| ₹10,000 | 5% | ₹500 | ₹10,500 |
Frequently asked questions
How do I calculate GST?
Multiply the net price by the GST rate and divide by 100. That is the GST amount. Add it to the net price to get the total. For 18%, GST on ₹1,000 is ₹180 and the total is ₹1,180.
How do I calculate GST from the total amount?
Divide the total (gross) by 1 plus the rate. At 18%, divide by 1.18. The result is the price before GST. The difference is the GST. Do not just take 18% off the total.
How do I calculate GST on MRP?
MRP already includes GST. Net price = MRP ÷ (1 + rate ÷ 100). GST = MRP − net price. Use the Remove GST option and enter the MRP.
How do I find the GST percentage?
Subtract the net price from the gross price, divide by the net price, and multiply by 100. Use the Find rate option and enter both prices.
What are the GST rates in India?
Most items are taxed at 5% or 18%. A small group of luxury and sin goods is at 40%. Gold and silver are 3%. Some items are 0%. The exact rate depends on the item or service, so check its HSN or SAC code.
What is CGST and SGST?
For a sale inside one state, GST is split equally between the central government (CGST) and the state (SGST). For a sale to another state, the full amount is IGST.
Is the GST rate the same in Australia, NZ and Singapore?
No. Australia is 10%, New Zealand 15% and Singapore 9%. Canada has a 5% federal GST, and some provinces add HST on top.
What is a reverse GST calculator?
A reverse GST calculator starts from the GST-inclusive price and works backwards to the price before GST. Choose Remove GST, enter the total and the rate, and it shows the net price and the GST amount.
Is GST the same as VAT?
They work the same way: a tax on the value added at each step, charged on the net price. The name differs by country. The same formulas apply to VAT.
About this calculator
Free GST calculator for India, Pakistan, Australia, New Zealand, Canada and Singapore. It runs in your browser and does not store your numbers. Last updated November 11, 2026. Questions or corrections: [email protected].
Written by Junaid Riaz
Junaid Riaz wrote and checked this page. Every formula and worked example on this page is shown in full so you can check each result yourself. Corrections are welcome at [email protected].
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For information only, not professional advice.
Written by Junaid Riaz. Last updated: November 11, 2026.