GST ka calculation simple hai. Ye post bata raha hai exact formula aur real examples.

GST Calculator Formula

Add GST (Inclusive/Exclusive)

Amount + GST = Amount × (1 + GST%/100)

Reverse GST (Extract from GST-inclusive price)

Base Price = Total × 100 ÷ (100 + GST%)

Examples

Example 1: ₹1,000 + 18% GST = ₹1,180. Try GST Calculator.

Example 2: ₹1,180 (incl 18%) → Base ₹1,000, GST ₹180.

FAQs

  • What is reverse GST? Inclusive price se GST nikalna.
  • Is this accurate? The formulas are exact for the rate you enter, but GST rates vary by product and service, and the calculator uses the rates published by the Government of India. Always check the exact rate for your product on the official GST portal (gst.gov.in) before invoicing or filing.

Worked example — tested on the live GST Calculator

I tested this on TooliFyra's GST Calculator. Enter ₹10,000, choose 18% and Add GST, and the tool gives GST of ₹1,800, CGST of ₹900, SGST of ₹900 and a total of ₹11,800. The split is simple: for a sale within the same state, the 18% is divided equally into 9% CGST and 9% SGST, so ₹900 + ₹900 = ₹1,800. For a sale to another state, the same ₹1,800 is charged as IGST instead.

Going the other way, I entered ₹11,800 as a GST-inclusive price at 18%. The tool gives an original price of ₹10,000 and GST of ₹1,800 (CGST ₹900 and SGST ₹900). That is the reverse calculation in practice: divide the inclusive price by 1.18. A common mistake is to take 18% of ₹11,800 (₹2,124) — that overstates the GST, because the 18% applies to the price before GST, not to the price that already includes it.

GST 2.0 slabs (from 22 September 2025)

Under GST 2.0, the rates in the calculator are 0%, 3% (gold and jewellery), 5% (merit rate), 18% (standard rate) and 40% (special rate). The old 12% and 28% slabs were removed on 22 September 2025. Most everyday goods and services fall under 5% or 18%, so check which slab your product is in before you quote a price — the rate, not the formula, is where most GST mistakes happen.

Which formula to use

  • Adding GST: use it when you quote a price before tax, for example a shop price of ₹10,000 plus GST.
  • Removing GST: use it when the price you see already includes GST, for example a bill of ₹11,800, and you need the pre-tax price for your accounts.
  • CGST + SGST or IGST: within one state the tax is split equally between the Centre and the state; between states it is charged as one IGST amount. The total is the same either way.