GST (Goods and Services Tax) replaced over a dozen central and state taxes in India since 2017. Understanding how to calculate GST is essential for business owners creating invoices, freelancers billing clients, and consumers wanting to verify their tax amount.
GST Slabs in India (2025)
0% GST: Essential food items, medical services, education | 5% GST: Basic food items like packaged food, transport | 12% GST: Processed food, business class air travel, computers | 18% GST: Most services, electronics, restaurants with AC | 28% GST: Luxury goods, automobiles, tobacco, casinos.
How to Add GST to a Price (GST Exclusive Calculation)
GST Amount = Original Price × GST Rate ÷ 100. Total Price = Original Price + GST Amount. Example: You sell a product for ₹1,000 and charge 18% GST. GST Amount = ₹1,000 × 18 ÷ 100 = ₹180. Final Invoice Amount = ₹1,000 + ₹180 = ₹1,180.
How to Remove GST from a Total (Reverse GST Calculation)
If a price already includes GST and you want to find the original price: Original Price = Total Price × 100 ÷ (100 + GST Rate). Example: You paid ₹1,180 including 18% GST. Original Price = ₹1,180 × 100 ÷ 118 = ₹1,000. GST Amount = ₹1,180 – ₹1,000 = ₹180.
CGST, SGST and IGST — What Is the Difference?
For intra-state sales (seller and buyer in same state): The GST is split equally between CGST (Central GST) and SGST (State GST). For 18% GST: CGST = 9% + SGST = 9%. For inter-state sales (seller and buyer in different states): IGST (Integrated GST) = full GST rate = 18%.
Frequently Asked Questions
What is the GST rate on software services and freelancing?
Software services and most IT/freelancing services attract 18% GST. If your annual turnover exceeds ₹20 lakh (₹10 lakh in special states), GST registration is mandatory.
Do I need to pay GST on Amazon and Flipkart purchases?
The GST is already included in the price you see on these platforms. The seller pays GST to the government. As a consumer, you pay the price shown without any additional GST.
What is the GST on restaurant food?
Non-AC restaurants: 5% GST (no input tax credit). AC restaurants and those inside hotels with room rent over ₹7,500: 18% GST.
Is GST applicable on rent for residential properties?
GST is not applicable on residential rent for tenants living in the property. Commercial property rent attracts 18% GST if the landlord is GST registered.