GST calculator
Add GST to a price, or work backwards from a GST-inclusive total, with the CGST and SGST split.
GST calculator
Works offlineWithin a state, GST is split equally into CGST and SGST; between states it is charged as IGST.
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Adding and removing GST
To add GST: GST amount = price × rate ÷ 100, and the total = price + GST. For ₹10,000 at 18%, GST is ₹1,800 and the total is ₹11,800.
To remove GST from a GST-inclusive price: price before GST = total × 100 ÷ (100 + rate). For ₹11,800 at 18%, the price before GST is ₹10,000. Pick “Incl. GST” in the calculator to do this directly.
CGST, SGST and IGST
When the seller and buyer are in the same state, the tax is split equally between the Centre (CGST) and the State (SGST) — an 18% GST is 9% CGST + 9% SGST. When goods or services move between states, the whole amount is charged as IGST. The total tax is the same either way.
Which GST rate applies?
Most goods and services fall under a small number of slabs, with special lower rates for items such as precious metals and zero or nil rates for some essentials. Rates and classifications are revised from time to time by the GST Council, so check the current rate for your item or service on the official GST portal (gst.gov.in) or with your chartered accountant before billing.
Frequently asked questions
How do I calculate 18% GST on an amount?
Multiply the amount by 0.18 to get the GST, then add it to the amount. Or enter the amount and 18 in the calculator above.
How do I find the price before GST from a bill total?
Choose “Incl. GST”, enter the total and the rate. The calculator shows the base price and the tax inside the total.
What is the difference between CGST, SGST and IGST?
CGST and SGST are charged together on sales within one state (each is half of the rate). IGST is charged on sales between states. The total tax is the same.
Is this calculator a substitute for professional advice?
No. It does arithmetic only. Rates, exemptions, input tax credit and invoicing rules depend on your situation, so confirm with the GST portal or a professional.
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Page reviewed 25 October 2026.