How to Calculate GST in India: A Complete Step-by-Step Guide

GST (Goods and Services Tax) has been in force in India since July 2017, but many business owners and professionals still struggle with GST calculations — especially distinguishing inclusive vs exclusive amounts, and CGST/SGST vs IGST splits.

GST Rate Slabs in India

• 0%: Essential food items, books, medical equipment
• 5%: Household necessities, economy travel, restaurants
• 12%: Processed food, business class travel, some textiles
• 18%: Most services, electronics, restaurants (AC), telecom
• 28%: Luxury goods, automobiles, tobacco, aerated drinks

Calculating GST Exclusive (Adding GST)

If price before GST is ₹1,000 at 18%: GST amount = 1000 × 18/100 = ₹180 Total price = ₹1,180

Calculating GST Inclusive (Extracting GST)

If a bill total is ₹1,180 and GST rate is 18%: Base price = 1180 / 1.18 = ₹1,000 GST amount = 1180 − 1000 = ₹180

CGST/SGST vs IGST

• Within same state (intrastate): Split equally between CGST (Central) and SGST (State). 18% GST → 9% CGST + 9% SGST.
• Between different states (interstate): IGST (Integrated GST) applies. 18% GST → 18% IGST (no split).

Input Tax Credit (ITC)

Businesses registered for GST can claim a credit for GST paid on inputs (purchases) against GST collected on outputs (sales). This prevents cascading taxation. Proper invoice management is essential for ITC claims.

Calculate GST instantly with our GST Calculator.