GST Calculator — add or remove GST instantly
Split any amount into CGST, SGST or IGST at 5%, 12%, 18% or 28%.
Off = CGST + SGST within the same state
GST breakdown
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How GST is calculated in India
GST is charged as a percentage of the taxable value of a supply. If your price is exclusive of GST, the tax is added on top: GST = taxable value × rate. If the price you quote already includes GST, the tax hidden inside it is: GST = amount × rate ÷ (100 + rate).
The rate itself is split depending on where the supply lands. For a supply inside the same state (intra-state), the tax is divided equally into CGST and SGST — an 18% supply becomes 9% CGST plus 9% SGST. For a supply that crosses a state border (inter-state), the whole 18% is charged as a single IGST line.
Which GST rate applies to you
The five common slabs are 0%, 5%, 12%, 18% and 28%. Most professional and IT services fall in 18%. Restaurants without input credit are at 5%. Packaged food, apparel below ₹1,000 and economy transport sit at 5% or 12%. Luxury goods, aerated drinks and tobacco attract 28% plus cess.
Getting the rate wrong is one of the most common reasons a GST notice arrives. If your product mix spans multiple HSN codes, it is worth having a chartered accountant confirm the classification once rather than correcting it across a year of invoices.
Frequently asked questions
How do I remove GST from an inclusive amount?
Divide the inclusive amount by (1 + rate/100). For example, ₹1,180 at 18% gives a base of ₹1,000 and GST of ₹180. Our calculator does this automatically when you pick 'GST inclusive'.
When is IGST charged instead of CGST and SGST?
IGST applies when the place of supply is in a different state from the supplier's location, and on imports. Within one state, the same total rate is split half into CGST and half into SGST.
Is GST calculated on the discounted price?
Yes. Discounts shown on the face of the invoice are deducted before GST is applied. Post-sale discounts only reduce the taxable value if they were agreed before the supply and are linked to specific invoices.
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