FinCalculator
Business & SME APIWeb Calculator UI

Free GST Amount & Rate Calculator API (2026)

GST calculation API for inclusive and exclusive price calculations.

Interactive API Playground & Live Test

GET/api/v1/gst

Query Parameters

Amount in ₹: before GST, or including GST when inclusive=true

GST rate % (5, 18, 40)

Set "true" if amount includes GST, to take the GST out (default: false)

Set "true" for an inter-state supply: IGST instead of CGST + SGST (default: false)

curl -X GET "https://fincalculator.in/api/v1/gst?amount=10000&rate=18&inclusive=false&interstate=false" \
  -H "Accept: application/json"
Live JSON Response (HTTP 200 OK)
Click "Execute Live API Request" below...

Request Parameters Schema

ParameterTypeRequiredDescription / Notes
amountnumberRequiredAmount in ₹: before GST, or including GST when inclusive=true
ratenumberRequiredGST rate % (5, 18, 40)
inclusivebooleanOptionalSet "true" if amount includes GST, to take the GST out (default: false)
interstatebooleanOptionalSet "true" for an inter-state supply: IGST instead of CGST + SGST (default: false)

Related Business & SME APIs

GET /api/v1/gst-itcFree GST Input Tax Credit (ITC) Calculator APIGET /api/v1/edf-deadlineFree EDF (Export Declaration Form) Deadline APIGET /api/v1/invoiceFree GST Invoice Totals API (CGST, SGST, IGST)GET /api/v1/startup-burn-rateFree Startup Burn Rate & Cash Runway API

Frequently Asked Questions (FAQs)

Is the Free GST Amount & Rate Calculator API free to use in production apps?
Yes! All FinCalculator REST APIs are completely free, zero-auth, open-CORS, and edge-cached for high performance across global web and mobile applications.
What is the rate limit for /api/v1/gst?
Endpoints are cached at the edge for 24 hours. There are no restrictive rate limits for standard web traffic and mobile applications.