GST Calculator
Add or remove GST in a click — with the CGST/SGST or IGST split worked out for you. Free, instant, no login.
Result
PeppyBooks applies the right GST — and the IGST/CGST/SGST split — to every invoice automatically, and e-invoices it in real time.
Get GST right automatically — Start free trialHow to calculate GST
Goods and Services Tax (GST) in India is charged as a percentage of the taxable value of a supply. To add GST, multiply the base amount by the rate and add it back: a ₹1,000 sale at 18% GST becomes ₹1,000 + ₹180 = ₹1,180. To remove GST (reverse GST) from a price that already includes tax, divide the gross by (1 + rate): ₹1,180 at 18% gives a base of ₹1,000 and GST of ₹180.
CGST, SGST and IGST — which applies?
The split depends on where the supply goes:
- Intra-state (same state): GST is split equally into CGST (central) and SGST (state). An 18% rate becomes 9% CGST + 9% SGST.
- Inter-state (different states): the full rate is charged as a single IGST. 18% is charged as 18% IGST.
The calculator above shows the correct split as you change the supply type.
Common GST rates in India
Most goods and services fall under 5%, 12%, 18% or 28%, with some items at 0% (exempt or zero-rated). The right rate depends on the item's HSN/SAC classification. Always confirm the applicable rate for your products with the current GST schedule.
Stop calculating GST by hand
A calculator is handy for a one-off number — but on every invoice, doing this manually is slow and error-prone. PeppyBooks GST billing software applies the correct rate and CGST/SGST/IGST split automatically, generates the e-invoice with IRN and QR code, and posts it straight to your books. See India GST accounting or start a free 14-day trial.