How GST calculation works
For an amount before GST, GST is calculated by multiplying the taxable amount by the GST rate. For an amount that already includes GST, the taxable value can be derived from the inclusive total.
CGST, SGST and IGST
For an intra-state supply, GST is commonly split into CGST and SGST. For an inter-state supply, IGST may apply. The exact tax treatment depends on the transaction and applicable Indian tax rules.