Add GST to a price, or work backwards from a GST-inclusive price. See the CGST and SGST halves, or IGST for inter-state supplies.
To add GST: GST = price × rate ÷ 100 and total = price + GST. To remove GST from an inclusive price: base = total × 100 ÷ (100 + rate). Within one state the tax is split equally into CGST and SGST; between states it is IGST.
After the GST 2.0 reform effective 22 September 2025, the main rates are 5%, 18% and 40%, with 0% for nil-rated items and special rates of 3% and 0.25% for some goods. Rates change and rules differ; verify with the tax authority or an accountant.
It depends on the HSN/SAC code of the goods or service. Check the current rate schedule.
CGST+SGST apply within a state; IGST applies to inter-state supplies.