How to use it
- Choose “Add GST” if your amount is before tax, or “Remove GST” if it already includes GST (like an MRP).
- Enter the amount and tap the GST rate, or choose Custom to type any rate.
- Pick Intra-state (CGST + SGST) or Inter-state (IGST) to see how the tax is split.
- Read the total or base price, the GST amount and its split, with the formula and your numbers below.
GST exclusive vs GST inclusive
An amount is exclusive of GST when tax still has to be added on top — common in quotations and B2B price lists. It is inclusive when the tax is already inside it, as with the MRP on a packet or most prices shown to shoppers. The calculator works both ways.
How to add GST
GST = Amount × Rate ÷ 100, and Total = Amount + GST.
Example: a service priced at ₹1,000 with 18% GST. GST = 1,000 × 18 ÷ 100 = ₹180, so the invoice total is ₹1,180.
How to remove GST from an inclusive price
Amount before GST = Total × 100 ÷ (100 + Rate), and GST = Total − Amount before GST.
- ₹1,180 including 18% GST: 1,180 × 100 ÷ 118 = ₹1,000, so the GST is ₹180.
- ₹2,500 including 5% GST: 2,500 × 100 ÷ 105 = ₹2,380.95, so the GST is ₹119.05.
A common mistake is to take 18% of the inclusive price: 18% of ₹1,180 is ₹212.40, which overstates the tax by ₹32.40. The GST was charged on ₹1,000, not on ₹1,180, so you must divide by 1.18 instead.
CGST, SGST and IGST
| Type of sale | Tax charged | ₹1,000 at 18% |
|---|---|---|
| Within the same state (intra-state) | CGST + SGST, half the rate each | ₹90 CGST + ₹90 SGST |
| Between two states (inter-state) | IGST at the full rate | ₹180 IGST |
The total tax is the same either way; only the split between the Centre and the state changes. In union territories without their own legislature, UTGST takes the place of SGST.
GST rate slabs
GST rates were rationalised in 2025. The broad structure now looks like this, but rates for individual items change through official notifications — always check the latest rate on the CBIC website or with your tax adviser before you bill.
| Rate | Generally used for |
|---|---|
| Nil / exempt | Some essential goods and services |
| 5% | Many everyday goods and some services |
| 18% | The standard rate for most goods and services |
| 40% | A special rate for selected luxury and “sin” goods |
| 12% and 28% | Main slabs before the 2025 revision; you will still see them on older invoices |
| Special rates | A few items carry special low rates, such as 3% or 0.25% |
This calculator works out GST only. It does not include any cess or other charges that may apply to some goods.