How to Remove GST From an Inclusive Price

Reverse GST recovers the pre-tax base from the total

When a displayed price already includes GST, the GST portion is not found by subtracting the rate percentage from the total. The calculator's inclusive mode recovers the taxable base and then derives GST as the difference between total and base.

Use the inclusive mode in the GST Calculator when the entered amount already includes the selected rate.

Example: ₹1,180 inclusive at 18%

The engine-derived result for ₹1,180.00 inclusive at 18% is a taxable base of ₹1,000.00 and GST of ₹180.00. With intra-state selected, CGST is ₹90.00 and SGST is ₹90.00.

Why subtracting 18% from ₹1,180 is not the reverse calculation

The 18% rate applies to the pre-tax base, not to the GST-inclusive total. The inclusive total is therefore the base plus 18% of that base. Subtracting 18% of the total answers a different question and does not recover the original base.

The engine keeps full internal precision and the interface formats the displayed currency values.

The transaction selector remains an assumption

The selected intra-state mode splits the calculated GST equally into CGST and SGST. Selecting inter-state would show the full calculated amount as IGST. The calculator does not determine legal place of supply, classification, exemption, cess or reverse-charge treatment.

For the wider arithmetic scope, read GST Explained. If an invoice differs, see Why a GST Calculator May Differ From an Invoice.