GST calculator
Add or remove GST, without the mental maths.
Amount including GST
For illustration only. Read the assumptions below for the full picture.
Understand your result.
Add GST to a base amount or remove it from a GST-inclusive amount. Choose intra-state or inter-state treatment to see the arithmetic tax split.
Confirm whether your entered price is before or after GST. The tool calculates an entered rate; it does not classify the supply or determine the legally correct rate.
A worked example.
Using this calculator’s default inputs, amount including gst is ₹11,800. This is an illustration of the stated formula, not a forecast.
See the example inputs
| Investment amount | ₹10,000 |
|---|---|
| Applicable GST rate | 18 % |
| The entered amount is | Before GST — add GST |
| Supply type | Intra-state — CGST + SGST |
A common mistake to avoid
Adding GST again to an invoice total that already includes it.
Questions you might have.
Does it include compensation cess or reverse charge?
No. Those issues, input tax credits and supply-specific exemptions are outside this arithmetic helper.
Are CGST and SGST always displayed?
Only for the selected intra-state scenario. The inter-state option shows IGST instead.
Prepared by INDwise · Calculation checks: 29 October 2026 · How we check the maths · Report a correction
How we calculate it
Exclusive: GST = base × rate. Inclusive: base = total ÷ (1 + rate). Intra-state tax is split equally between CGST and SGST; inter-state tax is shown as IGST.
Assumptions & things to know
Arithmetic helper only. Confirm classification, place of supply, rate, exemption and cess independently. No compensation cess, reverse charge, input tax credits or invoice rounding adjustment.
Your privacy & sharing
Your financial inputs are used only within this page. Saved calculators use this browser’s local storage. Sharing creates a link with the entered values, so anyone with that link can see those values. A downloaded summary stays on your device.