Finance Guide

Manual GST Calculation

Understand the math behind India's Goods and Services Tax slabs.

GST (Goods and Services Tax) is an indirect tax used in India on the supply of goods and services. Understanding how to calculate it manually is essential for business owners, accountants, and students. Whether you are adding GST to a base price or extracting it from a total amount, the formulas are straightforward.

1. Adding GST (Exclusive)

To add GST to the base price of a product, use the following formula:

GST Amount = (Original Cost × GST %) / 100
Net Price = Original Cost + GST Amount

Example: If the cost of a service is ₹1,000 and the GST rate is 18%:
GST = (1000 × 18) / 100 = ₹180.
Total Price = ₹1,000 + ₹180 = ₹1,180.

2. Removing GST (Inclusive)

If you have a total price that already includes GST and you want to find the base price, use this formula:

GST Amount = Total Price - [Total Price × {100 / (100 + GST %)}]
Base Price = Total Price - GST Amount

Example: If the total price is ₹1,180 and the GST rate is 18%:
Base Price = 1180 - [1180 - (1180 × (100/118))] = ₹1,000.
GST Amount = ₹180.

Common GST Slabs in India

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