GST Calculator: How GST Works in India (Complete Guide)

How GST Works in India

GST (Goods and Services Tax) replaced a web of central and state taxes in July 2017 with a single, unified tax on the supply of goods and services. It is a destination-based tax — collected where the goods are consumed, not where they are produced.

This guide explains the slabs, the components, and how to calculate them with the GST calculator.

The Four GST Rates in India

Rate	Typical goods
0%	Unprocessed food, books, newspapers
5%	Packaged food, transport services, small appliances
12%	Computers, processed food, room tariffs
18%	Most services, electronics, clothing
28%	Luxury cars, tobacco, aerated drinks

Most everyday services and products fall in the 5–18% band.

CGST, SGST, and IGST Explained

• Intra-state sale (seller and buyer in the same state) — the tax splits equally into CGST (central) and SGST (state).
• Inter-state sale (different states) — the full tax is IGST (integrated), which the centre then redistributes.

For a ₹10,000 intra-state sale at 18%: CGST ₹900 + SGST ₹900. For an inter-state sale: IGST ₹1,800. Total tax is always the same — only the split changes.

How to Calculate GST

On the GST calculator:

1. Pick the rate (5%, 12%, 18%, or 28%).
2. Enter the base price.
3. Get the GST amount and the total.

You can also reverse it — enter a GST-inclusive price and the tool extracts the base amount and tax inside it. This matters for input tax credit (ITC) claims.

GST and Your Invoices

Every registered business must issue proper tax invoices showing the tax split. Pair the calculator with the GST invoice generator to produce compliant bills automatically, and verify your CGST/SGST/IGST numbers before filing monthly returns.

Frequently Asked Questions

• Do I need GST registration? Businesses above the turnover threshold (currently ₹40 lakh for goods, ₹20 lakh for services in most states) must register.
• Can individuals claim input tax credit? ITC is for registered businesses claiming tax paid on their purchases.
• Is the calculator free? Yes, the GST calculator is free.

Master GST the easy way — calculate any amount in seconds with the free GST calculator.