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GST Calculator

Choose whether you are adding GST to a price or taking it out of one, enter the amount and pick the rate. For Indian invoices the calculator also splits the tax into CGST and SGST for a sale within a state, or IGST for a sale between states.

What do you want to do?
Supply type

Enter a price and a rate to work out the GST.

How to use this tool

  1. Choose “Add GST” if you have a price before tax, or “Remove GST” if you have a price that already includes GST.
  2. Enter the amount.
  3. Enter the GST rate or tap one of the common rates. Confirm the rate for your product or service — it depends on its HSN or SAC classification.
  4. For an Indian invoice, choose whether the supply is within a state or between states.
  5. Read the net price, GST amount and gross price, with the CGST and SGST or IGST breakdown.

Formula and method

Adding GST

GST = Net × rate ÷ 100;  Gross = Net + GST

Removing GST

Net = Gross × 100 ÷ (100 + rate);  GST = Gross − Net

Taking 18% off a GST-inclusive price does not give the pre-tax price, because the 18% was charged on the smaller net amount. The GST inside a gross price is rate ÷ (100 + rate) of it: 18 ÷ 118 of the total at 18%.

Splitting the tax

Within a state: CGST = SGST = GST ÷ 2;  Between states: IGST = GST

Worked examples

Adding 18% GST to ₹1,000

  1. GST: 1,000 × 18 ÷ 100 = ₹180
  2. Gross: 1,000 + 180 = ₹1,180
  3. Within a state: CGST ₹90 (9%) + SGST ₹90 (9%)

₹1,180 including GST, with ₹90 each of CGST and SGST.

Finding the pre-GST price of ₹1,180

  1. Net: 1,180 × 100 ÷ 118 = ₹1,000
  2. GST: 1,180 − 1,000 = ₹180
  3. The common mistake: 1,180 × 18% = ₹212.40, giving a wrong net of ₹967.60

₹1,000 before GST — not ₹967.60.

Notes and limitations

  • From 22 September 2025 India's main GST slabs are 5% and 18%, with a 40% rate for a small set of luxury and sin goods, after the GST Council merged the earlier 12% and 28% slabs. Some items remain exempt, and gold and precious stones have their own low rates.
  • The correct rate depends on the exact classification of what you sell. The quick-pick buttons are shortcuts, not a statement about any product.
  • GST compensation cess ended on 1 February 2026. Tobacco and pan masala now carry a separate excise duty or cess outside GST, which this calculator does not include.
  • The same calculator works for GST in Australia (10%), New Zealand (15%), Singapore (9%) and Canada — enter the rate and ignore the CGST/SGST split.

Frequently asked questions

How do I calculate GST from a total amount?

Divide the total by (1 + rate ÷ 100) to get the price before GST, then subtract that from the total. At 18%, divide by 1.18: ₹1,180 ÷ 1.18 = ₹1,000, so the GST is ₹180.

What is the difference between CGST, SGST and IGST?

For a sale within one state, the GST is split equally between the Central Government (CGST) and the State (SGST, or UTGST in a union territory). For a sale from one state to another, a single Integrated GST (IGST) is charged at the full rate. The customer pays the same total either way.

What are the current GST rates in India?

Since 22 September 2025 most goods and services fall under 5% or 18%, with 40% for a short list of luxury and sin goods, and some essentials exempt. Rates can change at GST Council meetings, so confirm the rate for your item on the CBIC website.

Is GST charged on the discounted price?

Yes, when the discount is shown on the invoice at the time of sale. GST is charged on the transaction value after such a discount, so apply the discount first, then add GST.

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