Free GST Calculator India (2026) — Inclusive & Exclusive

CGST and SGST: How India's GST Splits Between Governments

India's GST is one rate split between two governments. For intra-state supplies, the rate divides exactly in half: half to the centre as CGST, half to the state as SGST. So 18% becomes 9% CGST plus 9% SGST. For inter-state supplies, IGST (Integrated GST) is charged instead—the full 18% rate, apportioned later between the centre and the destination state. Your invoice must show the correct heads: CGST/SGST for intra-state, IGST for inter-state. The total tax is identical either way; only the revenue allocation changes.

Reverse GST: Extracting Tax from Inclusive Prices

To strip GST from a price that already includes it, divide, not subtract. At 18%, a GST-inclusive ₹11,800 divides as: 11,800 ÷ 1.18 = ₹10,000 net, leaving ₹1,800 in tax (₹900 CGST + ₹900 SGST). Subtracting 18% instead would understate the net and overstate the tax—a common error that triggers input credit disputes. This calculator's inclusive mode automates the division.

The Four GST Slabs

5% covers essentials and most food. 12% covers mid-tier goods and services. 18% is the most common rate, applied to most services. 28% applies to luxury and demerit goods, sometimes with additional cess. Choosing the wrong slab is a compliance error, not a rounding issue, and it affects your customer's input credit as much as your own liability. The rate follows the HSN code for a good or the SAC code for a service, so check the classification for what you actually supply rather than assuming 18%.

What This Tool Does (and Doesn't)

This calculator adds GST to net amounts and reverses it from inclusive prices, splitting tax into CGST and SGST. It does not determine the correct rate for an HSN or SAC code, model compensation cess, or handle reverse charge or registration thresholds. Use the invoice generator to lay out a compliant invoice, and the income tax calculator for the direct-tax side of the same business. For classification and compliance, consult a tax professional or the GST portal.