Calculate GST on a base price
For a base price of ₹1,000 and a GST rate of 18%, the GST amount is ₹180 and the GST-inclusive price is ₹1,180.
Find the GST-inclusive price
Find the base price from an inclusive amount
When the displayed price already includes GST, the base amount must be derived using the applicable GST rate rather than simply subtracting the rate percentage from the total.
Use the calculator
Use the GST Calculator for quick calculations, then browse Finance Calculators for other money-related tools.
GST treatment can depend on the goods or service classification, transaction type and effective date. Rate changes for many goods and services took effect on 22 September 2025, but special rates, exemptions and exceptions remain. Do not assume that a familiar percentage applies to every supply.
Check the official CBIC GST rates for goods and the Ministry of Finance FAQ on the 2025 GST rate changes. The calculator is a mathematical aid, not a tax classification or filing decision.
Worked examples
Example 1 — add 5% GST: For a taxable value of ₹2,000, GST is ₹2,000 × 5 ÷ 100 = ₹100. The total including GST is ₹2,100.
Example 2 — remove included 18% GST: If the invoice total is ₹1,180, the pre-GST value is ₹1,180 × 100 ÷ 118 = ₹1,000 and the GST component is ₹180. Do not calculate the tax by subtracting 18% of ₹1,180.
How to check a result
- Confirm whether the entered price is before or after GST.
- Use the rate that applies to the actual goods or service and transaction.
- Check whether the transaction is intra-state (often split into CGST and SGST) or inter-state (often IGST), as applicable.
- Compare the calculated values with the invoice and applicable official guidance.
What this calculator does not decide
A mathematical result does not determine the legally applicable GST rate, exemptions, place of supply, input-tax-credit eligibility or filing treatment. Those depend on the facts and current rules. Confirm compliance questions with official GST resources or a qualified tax professional.