Free tool
GST calculator
Add GST to a price, or find the GST inside an amount that already includes it. Works at every rate, with the CGST + SGST or IGST split.
Runs in your browser. Nothing you type is sent to billinginfo.
How the calculator works
Adding GST. GST = amount × rate ÷ 100. On ₹10,000 at 18%, GST is ₹1,800 and the total is ₹11,800.
Removing GST. When a price already includes GST, the tax inside it is amount × rate ÷ (100 + rate). On ₹11,800 at 18%: 11,800 × 18 ÷ 118 = ₹1,800, so the value before tax is ₹10,000. A common mistake is to take 18% of ₹11,800 (₹2,124): that overstates the tax.
CGST + SGST or IGST. A sale inside your own State carries CGST and SGST (or UTGST), each half the rate: 9% + 9% for 18%. A sale to another State, or an export, carries IGST at the full rate. The place of supply decides which; see our guide to place of supply.
Rounding. Each half is rounded to the paisa on its own, as it is printed on the bill, so CGST and SGST are always equal. All arithmetic is exact decimal (no floating point), the same as in the billinginfo app.
Which rate applies?
From 22 September 2025 most goods are at 5% or 18%, with 40% for a short list of luxury and sin goods, and special rates such as 3% for gold and 0.25% for rough diamonds. Find your item’s rate with the HSN code finder and read the GST rates guide.
How do I calculate GST backwards from an inclusive price?
Multiply the inclusive price by rate ÷ (100 + rate). For 5% on ₹1,050: 1,050 × 5 ÷ 105 = ₹50 GST, and ₹1,000 before tax.
Is the GST on a bill rounded?
Tax is worked out to the paisa. Many businesses then round the invoice total to the nearest rupee and show the difference as “Round off”. This calculator shows the exact figures; the invoice generator also shows the round off.
Do I charge GST on top of MRP?
No. MRP already includes all taxes. If you sell at MRP, use “including GST” to see how much of the price is tax.
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