Reverse GST Calculator (Add or Remove GST)
Add or remove GST at any rate with a CGST/SGST split.
Enter an amount, pick a rate and see the tax and net value side by side. Inclusive mode works backwards from a price that already contains tax, exclusive mode adds it on top, and the breakdown shows how the tax splits between CGST and SGST on a local sale or lands as a single IGST line inter-state.
How to use GST Calculator
- 1
Enter the amount.
- 2
Pick the GST rate and whether the amount is inclusive.
- 3
Read the breakdown.
How GST is calculated
For an exclusive (pre-tax) amount the tax is simply the base value multiplied by the rate: GST = amount × rate ÷ 100, and the invoice total is amount + GST. On a ₹10,000 supply at 18%, the GST is ₹1,800 and the total is ₹11,800.
Within a state that tax is shared equally between CGST and SGST — ₹900 each in the example above. On an inter-state supply the same ₹1,800 is charged as a single IGST line instead.
Reverse GST calculation (tax-inclusive prices)
When the price you have already includes tax, you cannot just take 18% of it. The reverse formula is: base = total × 100 ÷ (100 + rate), and GST = total − base.
So a tax-inclusive price of ₹11,800 at 18% works back to a base of ₹10,000 and GST of ₹1,800. Switch the calculator to inclusive mode and it applies this formula for you.
GST inclusive vs exclusive amounts
Exclusive pricing quotes the value of the goods and adds tax at the invoice line — normal in B2B, where the buyer claims input credit. Inclusive pricing quotes one figure the customer pays, which is what most retail and MRP-style listings do.
Getting the two mixed up is the usual cause of an invoice that is off by exactly the tax amount, so set the mode before you read the result.
What to do next
- work out the price you need — set a pre-tax selling price from a target margin before GST is applied
- see what you actually earn — check profit per unit once shipping and platform fees are counted
- price a promotion — find the sale price and the effective percentage off
- Further reading: How to Calculate GST: Formula, Examples & GST Rates in India
About this tool
GST Calculator is part of the MyShopBuy business tools collection — a free suite built for people who need a reliable result in seconds, not another signup form. Add or remove GST at any rate with a CGST/SGST split. Processing happens entirely inside your browser using modern web APIs, so nothing is uploaded, queued or stored. That makes it fast enough for daily use and safe enough for sensitive documents.
There are no watermarks, no file-count limits and no paywalls. If you use it often, create a free account to keep favourites and history in sync across your devices.