How is GST calculated?
GST is calculated as a percentage of the base (pre-tax) price. To add GST, multiply the base price by the rate and add it on top. To remove GST from a total that already includes it, divide the total by (1 + rate/100) to find the base price, then the difference is the GST amount.
What's the difference between CGST, SGST and IGST?
For a sale within the same state, GST is split equally into CGST (Central GST) and SGST (State GST) — each half the total rate. For an interstate sale, the full amount is charged as IGST (Integrated GST) instead, with no split. This calculator shows the CGST + SGST split since that's the more common case for local billing.
Which GST rate should I use?
India uses a handful of standard slabs — 0%, 3% (gold and select items), 5%, 12%, 18% and 28% — depending on the good or service. Most professional services and consulting work fall under 18%. Check your specific HSN/SAC code if you're unsure which slab applies to what you're billing for.