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GST Calculator

Add GST to a price or pull it back out of one, split into CGST and SGST.

Runs in your browser — nothing you type is sent anywhere

₹
GST rate

Total including GST

₹1,180.00

18% GST is ₹180.00

Taxable value
₹1,000.00
GST at 18%
₹180.00
CGST (half)
₹90.00
SGST (half)
₹90.00
Invoice total
₹1,180.00

CGST and SGST are the central and state halves used when buyer and seller are in the same state. For a sale across state lines the same total appears as a single IGST line instead.

About the GST Calculator

GST works in two directions and people get one of them wrong constantly. Adding tax to a net price is straightforward multiplication. Extracting it from a price that already includes it is not — and applying the rate to the inclusive figure is the single most common mistake in invoicing.

To see why, take ₹1,180 including 18% GST. Multiplying by 18% gives ₹212.40, which is wrong. The actual tax is ₹180, because the ₹1,180 is 118% of the taxable value, not 100% of it. The correct extraction divides by 1.18 to recover the base first. The error grows with the rate, and at 28% it becomes substantial.

The result is split into CGST and SGST, the central and state halves, which is how an Indian invoice presents it when buyer and seller are in the same state. For a sale across state lines the identical total appears as a single IGST line instead — the amount is the same, only the presentation differs.

All the current slabs are offered: nil, 3%, 5%, 12%, 18% and 28%. Which applies depends on the goods or service, and that classification is a question for your accountant rather than a calculator.

Everything is worked out in your browser, so nothing about your invoicing is transmitted anywhere.

How to use the GST Calculator

  1. Choose the direction

    Add GST when your figure excludes tax. Remove GST when the price you have already includes it.

  2. Enter the amount

    Whatever figure you are starting from — the net price, or the gross one you need to break down.

  3. Pick the rate

    Tap one of the slabs. 18% covers most services; goods vary considerably by category.

  4. Read the breakdown

    You get the taxable value, the GST, its CGST and SGST halves, and the invoice total.

Frequently asked questions

How do I remove GST from a total?
Divide by one plus the rate, not by the rate. For 18%, divide the inclusive amount by 1.18 to get the taxable value, then subtract to find the tax. Multiplying the inclusive figure by 18% overstates the tax and is the commonest error in GST arithmetic.
What is the difference between CGST, SGST and IGST?
For a sale within one state the tax splits evenly into CGST for the centre and SGST for the state. For a sale between states the whole amount is charged as IGST instead. The total is identical either way — only how it appears on the invoice changes.
Which GST rate applies to what I sell?
It depends on the classification of the goods or service, and the slabs run from nil through 3%, 5%, 12% and 18% to 28%. Most services fall at 18%. The classification itself is a question for your accountant — a calculator cannot tell you which slab your product sits in.
Why does my invoice total differ by a rupee?
Rounding. GST is calculated per line item and rounded, so a total computed from the invoice sum can differ slightly from one computed on the grand total. Accounting software applies specific rounding rules that this calculator does not attempt to replicate.
Is this figure legally authoritative?
No. It is arithmetic, and it is correct arithmetic, but GST compliance involves classification, place of supply and input credits that no calculator addresses. Use it to check a number, not to file a return.

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