Reverse GST Calculator

Extracting GST from an inclusive price

Most retail prices in India are quoted inclusive of GST — the tax is already baked into the figure you pay. A reverse GST calculation unwinds that: it recovers the base price and reveals the exact GST hidden inside.

The key formula is a division, not a multiplication:

• Base price = Inclusive amount ÷ (1 + rate/100)
• GST embedded = Inclusive amount − Base price

Why you divide instead of multiply

A common mistake is to take, say, 18% of the inclusive total. But GST is charged on the base, not the gross. So on an 18% inclusive price the tax is actually 18/118 of the total — roughly 15.25% — which is exactly what dividing by 1.18 gives you. Taking 18% of the total would overstate the tax.

CGST, SGST and IGST

Once you have the embedded GST, how it is labelled depends on the transaction:

• Intra-state (same state): the tax splits equally into CGST and SGST — 9% + 9% for an 18% slab.
• Inter-state or imports: a single IGST at the full rate applies instead.

This tool shows the CGST/SGST split used on most local invoices.

When reverse GST is useful

You need this whenever a price is quoted GST-inclusive and you want the pre-tax value: reconciling MRP-based sales, recording purchases for input tax credit, filing expense claims, or simply verifying the tax printed on a receipt. To go the other way and add GST to a net price, use the standard GST calculator.