Free tool · ZYRO

GST calculator

Add GST to a price or remove it from a GST-inclusive amount, with the CGST, SGST or IGST split.

Amount before GST
₹10,000.00
CGST (9%)
₹900.00
SGST (9%)
₹900.00
Total GST
₹1,800.00
Total amount
₹11,800.00

How the GST calculation works

  • Add GST: GST = amount × rate ÷ 100. Total = amount + GST.
  • Remove GST: amount before GST = total ÷ (1 + rate ÷ 100). GST = total − amount before GST.
  • Within a state: GST is split into equal CGST and SGST.
  • Between states: the whole GST is IGST.

This calculator does the maths only. Check the rate for your item's HSN or SAC code before you invoice.

GST calculator: questions

GST maths, CGST, SGST and IGST.

Multiply the price by the GST rate and add it. For example, ₹10,000 at 18% GST is ₹10,000 + ₹1,800 = ₹11,800.

Divide the total by (1 + rate/100). For example, ₹11,800 including 18% GST is ₹11,800 ÷ 1.18 = ₹10,000 before GST, so the GST is ₹1,800.

For a sale within the same state, GST is split equally into CGST and SGST. For a sale from one state to another, the full amount is charged as IGST.

Since 22 September 2025, most goods and services fall under 5% or 18%, with a 40% rate for a small set of luxury and sin goods. Some items have special rates, such as 3% on gold, and some are exempt. Always check the rate for your item's HSN or SAC code.

Yes. It is free, needs no signup, and works in your browser.