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GST Calculator

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Slab

  • Price including GST - Split into CGST and SGST
  • Total GST - the tax on this invoice
  • CGST, half the rate - to the central government
  • SGST, half the rate - to your state government

Add GST to a price or pull it back out of an inclusive one, at the rates in force since September 2025, or at any older rate you type in. The CGST and SGST halves are shown separately for a sale inside your state, and as a single IGST line for a sale outside it.

About this GST calculator

Adding GST is easy arithmetic. Taking it back out is where invoices go wrong, because the tax inside an inclusive price is not the rate applied to that price. On an item sold for 11,800 rupees at 18 percent, the tax is 1,800 and not 2,124: you have to divide by 1.18 first. This does that for you and shows the taxable value it worked back to, so the figure on your invoice can be checked rather than trusted.

The split matters for filing. A sale inside your own state carries central GST and state GST at half the rate each, which is why an 18 percent invoice shows 9 percent CGST and 9 percent SGST. A sale to another state carries integrated GST at the full rate on one line instead. The total tax is identical either way, but the lines on the invoice and in your return are not. A trade discount shown on the invoice comes off before any of this, since GST is charged on the reduced taxable value: the discount calculator will work that figure back out of a price you have already paid.

How to add or remove GST

  1. Pick Add GST if you have a price before tax, or Remove GST if the price already includes it.
  2. Choose Within the state for CGST and SGST, or Other state for a single IGST line.
  3. Enter the amount, then tap a slab. You can also type any rate, including an old 12 or 28 percent for a pre 2025 invoice, and the slab buttons will let go.
  4. Read the taxable value, the tax and the invoice total. The line underneath shows the working.
  5. Press Copy breakdown to paste the lines straight into an invoice or a message.

Common questions about GST

How do you remove GST from an inclusive price?
Divide the inclusive price by 1 plus the rate, not by the rate. At 18 percent the taxable value is the price times 100 divided by 118, and the tax is what is left. Applying 18 percent to the inclusive price instead overstates the tax by about 18 percent of itself, which is the single most common GST mistake on a hand written invoice.

What is the difference between CGST, SGST and IGST?
They are the same tax collected by different governments. A supply inside one state is split in half: central GST to the centre and state GST to the state. A supply between two states is charged as integrated GST at the full rate, and the centre later shares it with the destination state. For a union territory without a legislature the state half is called UTGST instead.

Which slab applies to what?
Since 22 September 2025 there are three rates plus nil. Broadly: nil for unbranded staples and many essentials, 5 percent for basics, most transport and a large part of what used to sit at 12, 18 percent for the bulk of goods and services, and 40 percent for luxury and sin goods, which can also carry a cess on top. The 12 and 28 percent slabs no longer exist. The list is set by notification and does change, so check the HSN or SAC code for your item rather than guessing from the price.

Does it handle a cess or a reverse charge?
No. This works out GST at the rate you give. A compensation cess on tobacco, aerated drinks or large vehicles is an extra line at its own rate, and a reverse charge moves who pays rather than how much. For a cess, calculate the GST here and add the cess as a separate amount on the same taxable value.

Are my invoice amounts uploaded?
No. The arithmetic is JavaScript running on this page, so the amounts stay on your own device. Nothing is sent, logged or saved, and the page keeps working with your connection switched off.

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