Use this GST calculator to add GST to a price, or work out the price before GST from an amount that already includes it. It also splits the tax into CGST and SGST, and shows the Excel formula for each result.
- Price before GST
- GST amount
- CGST + SGST
Check the current GST rate for your item. Results are rounded to paise.
How GST is calculated
Adding GST: multiply the price by the rate to get the GST, then add it to the price. ₹1,800 + 18% GST is ₹1,800 + ₹324 = ₹2,124.
Removing GST: divide the inclusive price by 1 plus the rate. ₹2,124 ÷ 1.18 = ₹1,800. Don’t subtract 18% of ₹2,124: that gives ₹1,741.68, which is wrong.
GST formulas in Excel
| To calculate | Excel formula |
|---|---|
| GST on a price | =A2*B2 |
| Price including GST | =A2*(1+B2) |
| Price before GST | =A2/(1+B2) |
| GST inside an inclusive price | =A2*B2/(1+B2) |
| CGST or SGST | =A2*B2/2 |
Here A2 is the price and B2 is the GST rate, such as 18%. For step-by-step examples and a practice file, see GST calculation in Excel.
Current GST slabs
Since 22 September 2025, most goods and services are taxed at 5% or 18%, with 40% for a small group of luxury and sin goods, and special rates such as 3% for gold and silver. Rates for individual items change from time to time, so check the current rate for yours.
Frequently asked questions
What is the difference between CGST, SGST and IGST?
For a sale within one state, GST is split equally between the central government (CGST) and the state (SGST). For a sale between states, the full amount is IGST.
How do I calculate the price without GST?
Divide the price that includes GST by 1 plus the rate. For 18% GST, divide by 1.18.
Is GST calculated before or after a discount?
On the price after the discount. Apply the discount first, then add GST.