GST calculator: add or remove GST
Work out GST on any amount in seconds. Add GST to a net price, or find the price before tax from a GST-inclusive total, with the CGST and SGST or IGST split shown separately.
Everything runs on your device. Nothing you add or type is sent to any server.
How to use it
- 01
Choose Add GST if your amount is before tax, or Remove GST if it already includes GST.
- 02
Enter the amount and tap a GST rate, or type any other rate in the custom rate box.
- 03
Choose intra-state for a sale within the same state (CGST + SGST) or inter-state for a sale to another state (IGST). The breakup appears instantly.
How GST is calculated
To add GST, multiply the net amount by the rate and divide by 100: GST = amount × rate ÷ 100. For example, ₹1,000 at 18 % gives GST of ₹180 and a total of ₹1,180. Within a state, that tax is split equally into CGST of ₹90 and SGST of ₹90. For a sale to another state, the whole ₹180 is IGST.
To remove GST from an inclusive price, use GST = amount × rate ÷ (100 + rate). For ₹1,180 including 18 % GST, the tax is 1,180 × 18 ÷ 118 = ₹180, so the price before tax is ₹1,000. Taking 18 % off ₹1,180 would be wrong.
Amounts are rounded to two decimals (paise). For intra-state sales, CGST and SGST are each rounded and always equal, and the parts always add up to the total shown.
Current GST rates
Since 22 September 2025, GST has two main rates, 5 % and 18 %, plus 40 % for certain luxury and sin goods; some items are nil-rated. Special rates include 3 % for gold, silver and jewellery, 0.25 % for rough diamonds and loose precious or semi-precious stones, and 1.5 % for other diamonds. The presets are these rates, checked against the official notifications in November 2026. Some items have other rates or conditions; use the custom box for those. Your item's rate depends on its classification, so confirm it in the CBIC notifications or with your tax adviser.
Private and honest
Calculations run in your browser and nothing is sent anywhere. This tool is for quick estimates and checking invoices. It is not tax advice, and it does not handle cess, reverse charge or composition schemes.
Frequently asked questions
When do I charge CGST and SGST, and when IGST?
CGST and SGST apply together on intra-state supplies, and IGST on inter-state supplies. Whether a sale counts as intra- or inter-state depends on the place-of-supply rules, so check with a professional if unsure.
Why is removing 18 % not the same as subtracting 18 %?
GST is charged on the net price, not on the total. The inclusive price is 118 % of the net price, so you divide by 1.18 to find the net amount.
Can I use a rate that is not in the list?
Yes. Type any rate from 0 to 100 % in the custom rate box, for example an older rate for an old invoice.