How to use the GST Calculator
Enter an amount, choose whether it excludes or includes GST, and pick the rate. The calculator shows the taxable value, the GST amount and the total, plus the CGST + SGST split for sales within a state or IGST for inter-state sales.
Formulas used
Adding GST: GST = Amount × Rate ÷ 100; Total = Amount + GST.
Removing GST: Taxable value = Amount × 100 ÷ (100 + Rate); GST = Amount − Taxable value.
GST slabs were rationalised in September 2025 to mainly 5% and 18%, with a 40% rate for specified goods, while special rates such as 3% (gold) and 0.25% (rough diamonds) continue. Always confirm the rate for your HSN/SAC code on the official GST portal.
Frequently asked questions
How do I calculate GST on a price?
Multiply the price by the GST rate and divide by 100. For ₹1,000 at 18%, GST is ₹180 and the total is ₹1,180.
How do I remove GST from an inclusive price?
Divide the inclusive price by (1 + rate/100). For ₹1,180 including 18% GST, the taxable value is ₹1,000 and GST is ₹180.
When do I charge CGST + SGST and when IGST?
For a sale within the same state, GST is split equally into CGST and SGST (or UTGST). For a sale to another state, the full amount is IGST.
Is this calculator accurate for filing returns?
It performs the arithmetic correctly, but rates depend on your goods or services and can change. Confirm rates with official notifications or your tax adviser.