GST calculator
Add GST to a price, or take it out of one that already includes it, and split it into CGST and SGST or IGST.
Free, with no sign-up Worked out in your browser The working shown, line by line
The answer
| Working back from a tax-inclusive amount | |
| Amount, including tax | 11,800.00 |
| Rate | 18% |
| Divided by one plus the rate 11,800.00 ÷ 1.18 | 10,000.00 |
| Taxable value | 10,000.00 |
| CGST 9% | 900.00 |
| SGST or UTGST 9% | 900.00 |
| Invoice total | 11,800.00 |
- Intra-state, so the rate is split equally between the centre and the state.
Sections 9 and 15 of the Central Goods and Services Tax Act 2017, and section 5 of the Integrated Goods and Services Tax Act 2017.
How it is worked out
Where the amount is the value before tax, the tax is the value times the rate, and the invoice is the two added together.
Where the amount already includes the tax, the value is the amount divided by one plus the rate - 11,800 divided by 1.18 is 10,000 - and the tax is what is left. Taking 18% off 11,800 gives 9,676, which is wrong by the tax on the tax: it is the commonest GST mistake there is.
Within a state, the tax is split equally into central tax and state tax (or union territory tax). Between states, the whole of it is integrated tax. Which one applies is decided by the place of supply, not simply by where the buyer lives.
Worked example: An invoice of ₹11,800 that includes 18% GST, within the state
The value is ₹10,000 and the tax ₹1,800, split into ₹900 of CGST and ₹900 of SGST.
Questions
How do I take GST out of an amount that already includes it?
Divide the amount by one plus the rate. For 18%, divide by 1.18: ₹11,800 becomes ₹10,000 of value and ₹1,800 of tax. Multiplying by 18% and subtracting gives the wrong answer.
When is it CGST and SGST, and when IGST?
A supply within one state or union territory carries central tax and state or union territory tax, half the rate each. A supply between states, an import, or a supply to a special economic zone carries integrated tax at the whole rate. The place of supply rules decide which it is.
Which rate should I use?
The rate notified for the HSN code of the goods or the SAC code of the service. After the rationalisation from 22 September 2025 most goods and services are at 5% or 18%, with 40% for a short list; check the notified rate for the item rather than assuming it.
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