# How GST Works in India: Slabs, CGST, SGST and IGST Explained

> India's GST has five slabs and splits differently for intra-state and inter-state sales. Here's how to calculate it correctly — with a free tool that shows every split.

- URL: https://www.pyalm.com/blog/india-gst-calculator-guide
- Author: Fadhil Abdulla
- Category: Free Tools
- Published: 2026-06-20
- Updated: 2026-06-20

---

## GST in one page

Goods and Services Tax (GST) in India is a destination-based tax with five main slabs: **0%, 5%, 12%, 18%, and 28%**. The slab depends on the type of goods or services. The free [GST Calculator](https://www.pyalm.com/free-tools/gst-calculator) covers all of them.

## Adding and removing GST

To **add** GST, multiply the base price by (1 + slab/100):

> ₹1,000 × 1.18 = ₹1,180 at the 18% slab.

To **remove** GST from a GST-inclusive amount, divide by (1 + slab/100):

> ₹1,180 ÷ 1.18 = ₹1,000 base, so the GST is ₹180.

## CGST, SGST and IGST

This is the part that catches people out:

- **Intra-state sale** (within the same state) — GST splits equally into **CGST** (central) and **SGST** (state). On 18% GST, that's 9% CGST + 9% SGST.
- **Inter-state sale** (between states) — the full amount is charged as **IGST**.

The calculator shows the base, the total GST, and both the CGST/SGST and IGST splits at once, so you can read off whichever applies to your transaction.

## Keep your books clean as you grow

Calculating one invoice is easy. Tracking GST across hundreds of transactions, suppliers, and slabs is where good software pays for itself. Explore [Pyalm's free business tools](https://www.pyalm.com/free-tools) to keep your numbers tidy.

[Use the free GST Calculator](https://www.pyalm.com/free-tools/gst-calculator) | [More free tools](https://www.pyalm.com/free-tools)