How to calculate GST
GST (Goods and Services Tax) is added on top of the base price of goods and services. Within a state it's split equally into CGST and SGST. For inter-state sales it's charged as IGST at the full rate.
Remove GST: Net = Amount × 100 ÷ (100 + Rate) → GST = Amount − Net
Example
A product priced at ₹10,000 with 18% GST costs ₹11,800 (₹900 CGST + ₹900 SGST). If ₹11,800 is the inclusive price, removing GST gives back the ₹10,000 base.
Current GST slabs
After the GST rate rationalisation of September 2025, most goods and services fall under the 5% and 18% slabs, with a 40% rate for luxury and sin goods. Special rates such as 3% (gold and jewellery) still apply. Older 12% and 28% rates are included for past invoices. Always check the latest notification for your HSN/SAC code.
Frequently asked questions
How do I remove GST from a price?
Divide the inclusive price by (1 + rate/100). For 18% GST: ₹1,180 ÷ 1.18 = ₹1,000 base price, so the GST is ₹180.
What is the difference between CGST, SGST and IGST?
CGST and SGST are charged together on sales within a state, each at half the GST rate. IGST is charged at the full rate on sales between states.
Can I use this for invoices?
Yes, it's handy for quick checks. For filing returns, always confirm the applicable rate for your product's HSN/SAC code.