India's Goods and Services Tax shows up in nearly every invoice, quote and MRP — but whether a price "includes GST" changes the numbers completely, and getting it wrong means under-quoting a client or overpaying a supplier. This GST calculator works both directions: enter an exclusive amount to add GST and get the tax-inclusive total, or enter an inclusive amount to strip GST out and reveal the base price and tax component. For intra-state sales it splits the tax into CGST and SGST halves; for inter-state sales the same figure is IGST. It covers all standard slabs — 5%, 12%, 18% and 28% — plus custom rates for special cases.
The formulas
Example
₹10,000 base at 18% GST. Tax = ₹1,800 (CGST ₹900 + SGST ₹900). Total = ₹11,800. Reverse: ₹11,800 inclusive at 18% → base ₹10,000, tax ₹1,800.
GST slabs
5% — essentials, economy transport; 12% — processed foods, some services; 18% — most goods and services (the standard slab); 28% — luxury and sin goods. Always confirm the HSN/SAC code's slab for your specific item.
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Frequently asked questions
How do I remove GST from a total?
Divide by (1 + rate). ₹11,800 inclusive at 18%: ₹11,800 ÷ 1.18 = ₹10,000 base, ₹1,800 tax.
What is the difference between CGST, SGST and IGST?
Intra-state sales split GST equally into CGST (Centre) and SGST (State). Inter-state sales charge the combined amount as IGST.
What are the GST slabs in India?
0%, 5%, 12%, 18% and 28%, assigned by HSN/SAC code. 18% is the most common slab.
Do I need GST registration?
Generally yes if turnover exceeds ₹40 lakh for goods (₹20 lakh for services; lower in special-category states), or for inter-state supply regardless of turnover.