GST math trips people up in two specific ways: whether a price already includes tax or needs it added, and whether the tax splits into CGST+SGST or comes out as a single IGST line. This tool handles both, at any of the standard slab rates, and shows the split so an invoice line item matches what you calculated.

Inclusive vs exclusive

"Exclusive of GST" means the amount you entered is the pre-tax price. GST gets added on top and the total goes up. "Inclusive of GST" means the amount you entered is already the final price, so the calculator works backward to show how much of it was tax. Mixing these two up is the single most common GST calculation error.

CGST/SGST vs IGST

Intra-state supply (buyer and seller in the same state) splits GST evenly into CGST (central) and SGST (state), each exactly half the total rate. Inter-state supply charges the full rate as a single IGST line instead. The total tax collected is the same either way. Only the split changes.

What this tool doesn't do

It won't tell you which slab (0%, 5%, 12%, 18%, 28%, or an exempt/special rate) applies to a given product or service. That's an HSN/SAC classification question, one you verify against the current rate schedule. Nothing about the price alone determines it.

Frequently asked questions