How to use this GST calculator
Goods and Services Tax applies to almost every purchase and sale in India, yet working out the tax component — especially from a price that already includes it — trips up shoppers and small businesses alike.
This calculator handles both directions: adding GST to a base amount, and extracting the embedded tax from a GST-inclusive price, with a clear breakdown of net amount and tax.
Inclusive versus exclusive GST
In exclusive mode, GST is added on top of your base amount: tax = amount × rate ÷ 100. In inclusive mode, the price already contains GST, so the tax is extracted as amount × rate ÷ (100 + rate).
Choosing the wrong mode is the most common GST calculation error, which is why this tool makes the direction explicit.
GST rate slabs
India uses several rate slabs — commonly 5%, 12%, 18% and 28% — with some goods at 0% and a few attracting additional cess.
Enter the slab that applies to your product or service; the classification itself depends on the item and is set by the GST framework.
CGST, SGST and IGST
For sales within a state, the GST splits equally into Central GST and State GST. For inter-state sales, a single Integrated GST applies instead.
The total tax is the same either way; this calculator shows the combined figure, which you can split in half for the intra-state CGST and SGST components.