GST Calculator
Enter any GST rate. Choose whether your amount is before tax (add GST) or already includes it (remove GST).
Rules and formula last checked on 10 October 2026.
Fill in the fields — the answer appears as you type.
Think an answer is wrong? Report it with your inputs.
How it's calculated
- Add GST: GST = amount × rate ÷ 100; total = amount + GST
- Remove GST: pre-tax = amount ÷ (1 + rate ÷ 100); GST = amount − pre-tax
- Intra-state supply: CGST = SGST = GST ÷ 2. Inter-state: IGST = GST
Worked example
₹10,000 + 18% GST = ₹11,800 (₹900 CGST + ₹900 SGST).
Load this example into the calculatorAssumptions and limits
- Rate is entered by you; this tool does not decide which rate applies to an item.
- Cess, if any applies to your item, is not included.
Common questions
Why isn't removing 18% GST the same as taking 18% off?
Because GST was calculated on the smaller pre-tax amount. ₹11,800 ÷ 1.18 = ₹10,000, whereas 18% off ₹11,800 would give ₹9,676.