GST Calculator India — Add or Remove GST

This GST calculator works in both directions: add GST to a base price to get the invoice total, or remove GST from a tax-inclusive price (like an MRP) to recover the base amount and the tax inside it. Pick a slab — 0%, 3%, 5%, 12%, 18% or 28% — and it instantly shows the net amount, total GST, the CGST/SGST split and the gross amount. It runs fully in your browser with no sign-up, so quotes and invoice figures never leave your device.

Adding GST is simple multiplication: GST = base × rate ÷ 100. Extracting it is where people slip up — the calculator uses the correct reverse formula, GST = gross − gross ÷ (1 + rate ÷ 100). So a ₹1,180 price that includes 18% GST breaks into a ₹1,000 base and ₹180 tax (₹90 CGST + ₹90 SGST), not the ₹212.40 you would get by wrongly taking 18% of ₹1,180.

The slabs cover India's current structure and its history: since the GST rate rationalisation of 22 September 2025, most goods and services fall under the 5% and 18% slabs, with 3% for gold and silver and 0% for exempt items, while the older 12% and 28% rates remain in the list for checking pre-reform invoices and transition-period bills. The half-and-half CGST/SGST figures apply to intra-state supplies; for inter-state sales the same total is simply charged as one IGST amount.