GST calculator: add or remove GST
Add GST to a price, or take it out of a price that already includes it, with the CGST, SGST or IGST split. Free to use, no sign-up, and nothing you enter is stored.
Reviewed 22 October 2026
How it works
Use this when you need the tax inside a price or the price after tax. Choose Add GST when you know the amount before tax, or Remove GST when your price already includes tax, as most retail prices in India do. Then choose whether the sale is within your state (CGST and SGST) or to another state (IGST).
The calculator does not decide whether GST applies, which rate is correct or which HSN or SAC code to use. Confirm those with a qualified adviser.
Formula
- Add GST: GST = amount × rate ÷ 100, and total = amount + GST
- Remove GST: amount before tax = price including GST ÷ (1 + rate ÷ 100), and GST = price − amount before tax
- Within the state: CGST = SGST = GST ÷ 2. To another state: IGST = full GST
Worked example
Add GST: a ₹1,000 service at 18% has GST of ₹180 and a total of ₹1,180. Within the state that is CGST ₹90 + SGST ₹90; to another state it is IGST ₹180.
Remove GST: a kurta priced at ₹1,050 including 5% GST has a taxable value of ₹1,050 ÷ 1.05 = ₹1,000 and GST of ₹50 (CGST ₹25 + SGST ₹25).
How to use these calculators well
Keep every number on the same basis. If your selling price excludes GST, your cost should exclude input GST too. Mixing a tax-inclusive price with a tax-exclusive cost is the most common reason a margin looks better than it really is.
Use real numbers from your own records. Last month's bills, purchase invoices and appointment calendar give far better answers than guesses. vkRetA keeps those records for you, so the inputs for these calculators are already in your workspace.
- Values stay in your browser and are not stored
- Results are estimates for planning, not tax or accounting advice
Frequently asked questions
How do I take GST out of a price that already includes it?
Divide the price by 1 plus the rate. For 18%, divide by 1.18: a ₹1,180 price has a taxable value of ₹1,000 and GST of ₹180.
When is GST split into CGST and SGST, and when is it IGST?
Generally, a sale within your own state is split equally between CGST and SGST, and a sale to another state carries IGST. Confirm the place of supply with a qualified adviser.
Is this calculator free to use?
Yes. It is free, needs no sign-up and runs in your browser. The values you enter are not submitted or stored.
Does vkRetA do this arithmetic on my bills?
Yes. On every bill vkRetA works out GST per line with the CGST and SGST or IGST split, applies coupon rules and updates stock and customer history. The calculator is for planning before you set prices.
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