How GST Is Calculated in India (with Examples)

Last updated: August 2026

GST (Goods and Services Tax) is a percentage added to the price of most goods and services in India. The common rates are 5%, 12%, 18% and 28%.

Adding GST

The GST amount is the price multiplied by the rate. Add 18% GST to ₹1,000 → GST ₹180, total ₹1,180. Add 12% to ₹25,000 → GST ₹3,000, total ₹28,000.

Removing GST (reverse GST)

If you have a total that already includes GST, you divide rather than subtract. For ₹5,900 including 18% GST: base = 5,900 ÷ 1.18 = ₹5,000, and the GST portion is ₹900.

CGST, SGST and IGST

For a sale within a state, GST splits equally into CGST and SGST — so 18% becomes 9% + 9%. For a sale between states, a single IGST is charged at the full rate.