How do I find the GST inside an inclusive price?

Divide by one plus the rate, then subtract. At eighteen per cent, divide by 1.18. Taking eighteen per cent of the inclusive figure overstates the tax — the correct share is about 15.25 per cent of the total.

What is the difference between CGST, SGST and IGST?

Geography. A sale within one state splits the rate equally between central and state GST. A sale across state lines is integrated GST at the full rate. The total is the same either way; the recipients differ.

Which rate applies to my product?

That is a classification question decided by the HSN or SAC code, not a calculation. The GST Council revises rates periodically, so check the current notification rather than relying on last year's figure.

How should rounding be handled on an invoice?

Compute tax per line item and round each to two decimal places. Rounding the total instead gives a slightly different figure, and reconciliation systems will notice the difference.

GST Calculator

Add or strip GST and split it into CGST and SGST.

Everything runs inside your browser. Your files never leave your device.

Result

The result appears here as you type.

Ask about GST Calculator

Questions about what this tool does, which option to pick, or what it can and cannot handle.

The question you type here is sent to an AI provider to be answered — your files and whatever you put in the tool above are not, and the assistant cannot see them. Answers are generated and can be wrong. The tool itself is not guessing: it runs deterministic code on your device.

About the GST Calculator

India's goods and services tax replaced a stack of separate central and state levies in 2017. The arithmetic is simple in one direction and slightly awkward in the other, which is where a calculator earns its place.

Adding GST to a base price is a multiplication. Extracting it from an inclusive price is not, and it is the step people get wrong: with eighteen per cent GST, the tax component of an inclusive price is not eighteen per cent of it. The correct calculation divides by 1.18 to recover the base and subtracts, which gives about 15.25 per cent of the inclusive figure. Taking eighteen per cent of the total overstates the tax every time.

The split between CGST, SGST and IGST is determined by geography rather than by the amount. A supply within a state splits the rate equally between central and state GST — eighteen per cent becomes nine and nine. A supply across state lines is integrated GST at the full rate, going to the centre and then apportioned. Getting this wrong on an invoice is a common and correctable error, and the calculator shows both breakdowns.

The rate slabs are 0, 5, 12, 18 and 28 per cent, with the higher slabs carrying additional cess on some categories such as tobacco and large vehicles. Which slab applies to a given item is a classification question rather than a calculation one, and it changes — the GST Council revises rates periodically, so verify the current rate rather than relying on what it was last year.

For invoicing, rounding rules matter: tax is generally computed per line item and rounded to two decimal places, and totalling rounded figures gives a different answer from rounding the total.

How to use it

1Enter the amount and choose whether it already includes GST.
2Select the rate slab that applies to the item.
3Read the base, the tax and the total, along with the CGST and SGST split.
4Use the integrated figure instead when the supply crosses a state boundary.

Questions

How do I find the GST inside an inclusive price?: Divide by one plus the rate, then subtract. At eighteen per cent, divide by 1.18. Taking eighteen per cent of the inclusive figure overstates the tax — the correct share is about 15.25 per cent of the total.
What is the difference between CGST, SGST and IGST?: Geography. A sale within one state splits the rate equally between central and state GST. A sale across state lines is integrated GST at the full rate. The total is the same either way; the recipients differ.
Which rate applies to my product?: That is a classification question decided by the HSN or SAC code, not a calculation. The GST Council revises rates periodically, so check the current notification rather than relying on last year's figure.
How should rounding be handled on an invoice?: Compute tax per line item and round each to two decimal places. Rounding the total instead gives a slightly different figure, and reconciliation systems will notice the difference.