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How to Use a GST Calculator: Add or Remove GST Instantly (India 2025)

February 19, 20257 min readToolDost Team

Learn how to add GST to a price or remove GST from an MRP in India. Covers all GST slabs (5%, 12%, 18%, 28%) with examples and a free online calculator.

What is GST in India?

The Goods and Services Tax (GST) was introduced in India on July 1, 2017, replacing multiple indirect taxes. It is a unified tax levied on the supply of goods and services across India.

GST Slabs in India (2025)

  • 0%: Essential items โ€” raw food, books, health services
  • 5%: Basic necessities โ€” packaged food, domestic LPG, economy hotels
  • 12%: Standard goods โ€” butter, cheese, mobile phones, processed food
  • 18%: Most common โ€” restaurants, financial services, electronics, IT services
  • 28%: Luxury items โ€” cars, tobacco, aerated drinks, high-end hotels

Additionally, there's a 3% GST on gold and jewellery.

How to Add GST to a Price (GST-Exclusive Calculation)

If you know the base price (excluding GST) and want to find the final price:

GST Amount = Base Price ร— (GST Rate / 100)
Final Price = Base Price + GST Amount

Example: Software subscription costs โ‚น10,000 (excluding GST). GST rate is 18%.

  • GST Amount = โ‚น10,000 ร— 0.18 = โ‚น1,800
  • Final Price = โ‚น10,000 + โ‚น1,800 = โ‚น11,800

How to Remove GST from MRP (GST-Inclusive Calculation)

If you have an MRP that already includes GST and want to find the base price:

Base Price = MRP / (1 + GST Rate / 100)
GST Amount = MRP โˆ’ Base Price

Example: A restaurant bill is โ‚น944 (inclusive of 18% GST).

  • Base Price = โ‚น944 / 1.18 = โ‚น800
  • GST Amount = โ‚น944 โˆ’ โ‚น800 = โ‚น144

GST for Businesses: CGST, SGST, and IGST

GST in India is divided into three types:

  • CGST (Central GST): Goes to the central government
  • SGST (State GST): Goes to the state government
  • IGST (Integrated GST): Applied on inter-state transactions

For an intra-state B2B transaction with 18% GST: CGST = 9% + SGST = 9%. For inter-state: IGST = 18%.

Common GST Calculation Mistakes to Avoid

  • Confusing GST-inclusive and GST-exclusive prices
  • Applying the wrong GST slab for a product/service
  • Not accounting for both CGST and SGST in B2B invoices
  • Forgetting Input Tax Credit (ITC) on business purchases

Use the Free GST Calculator

Skip the manual math โ€” use the ToolDost GST Calculator. Simply enter the price and select the GST rate. The tool instantly shows:

  • GST amount
  • Price before GST (base price)
  • Price after GST (final price)
  • CGST and SGST breakdown

Frequently Asked Questions

Is GST applied on the discounted price?

Yes, GST is applied on the discounted selling price, not the original MRP, for most goods.

Who collects GST?

The seller collects GST from the buyer and deposits it with the government. Businesses with turnover above โ‚น20 lakh (โ‚น10 lakh for special category states) must register for GST.

Topics Covered

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