GST (Goods and Services Tax) affects every purchase and sale in India. Whether you are a business owner creating invoices, a freelancer billing clients, or a consumer checking your bill, understanding GST calculation is essential. India follows a multi-slab GST structure with rates of 5%, 12%, 18%, and 28% for different goods and services. Try the reverse GST calculator to extract base prices, or find the right HSN code for your products.

GST Rate Slabs in India — Common Items

5% GST

Packaged food items, tea, coffee, sugar, edible oil, medicine, railway tickets

12% GST

Butter, cheese, ghee, dry fruits, mobile phones, packed coconut water, business class air travel

18% GST

Soap, toothpaste, hair oil, capital goods, industrial intermediaries, restaurant bills (non-AC)

28% GST

Luxury cars, tobacco products, pan masala, aerated drinks, motorcycles (>200cc), betting

GST Calculation Examples for Different Scenarios

Base Price	GST Rate	GST Amount	CGST	SGST	Total (Inclusive)
₹500	5%	₹25	₹12.50	₹12.50	₹525
₹2,000	12%	₹240	₹120	₹120	₹2,240
₹10,000	18%	₹1,800	₹900	₹900	₹11,800
₹50,000	28%	₹14,000	₹7,000	₹7,000	₹64,000

For inter-state transactions, IGST replaces CGST + SGST. The total IGST equals the combined CGST + SGST amount.

GST Compliance Tips for Businesses

Register if Turnover Exceeds ₹40L

GST registration is mandatory if annual aggregate turnover exceeds ₹40 lakh (₹20 lakh for special category states). For service providers, the limit is ₹20 lakh.

File Returns on Time

GSTR-1 (outward supplies) is due by 11th of the following month, and GSTR-3B (summary return) by 20th. Late filing attracts a fee of ₹50 per day (₹25 CGST + ₹25 SGST).

Maintain Proper Invoices

GST-compliant invoices must include HSN/SAC code, GSTIN of both parties, place of supply, and tax breakup. E-invoicing is mandatory for businesses with turnover above ₹5 crore.

Claim ITC Within November

Input Tax Credit (ITC) for a financial year must be claimed in the return filed by 30th November of the following year. Unclaimed ITC lapses.

How GST Is Calculated

In plain words

Goods and Services Tax (GST) is a comprehensive indirect tax levied on the supply of goods and services in India. The total GST is split equally between CGST (Central GST) and SGST (State GST) for intra-state transactions, while IGST (Integrated GST) applies to inter-state transactions. GST rates in India are typically 5%, 12%, 18%, or 28%.

How the calculation works

GST Amount = (Original Cost × GST Rate) / 100

Total Price (Inclusive) = Original Cost + GST Amount

CGST = SGST = GST Amount / 2 (Intra-State)
IGST = GST Amount (Inter-State)

Example: Product Price ₹1,000, GST 18%
GST Amount = 1,000 × 18/100 = ₹180
CGST = ₹90, SGST = ₹90
Total = ₹1,180

A quick example

Let us calculate GST on a product worth ₹12,000 at 18% GST:

Product Price (Excluding GST):₹12,000

GST Rate:18%

Transaction Type:Intra-State (Same State)

Step by step

1.GST Amount = ₹12,000 × 18/100 = ₹2,160
2.CGST = ₹2,160 / 2 = ₹1,080
3.SGST = ₹2,160 / 2 = ₹1,080
4.Total Price (Inclusive) = ₹12,000 + ₹2,160 = ₹14,160

So the answer is: GST Amount = ₹2,160 | CGST = ₹1,080 | SGST = ₹1,080 | Total Price = ₹14,160

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Frequently Asked Questions

What is the difference between CGST, SGST, and IGST?

CGST (Central GST) and SGST (State GST) are levied together on intra-state supplies (same state). IGST (Integrated GST) is levied on inter-state supplies (different states) and imports. The total tax rate remains the same regardless of the split.

What are the GST slabs in India?

India has four main GST slabs: 5% (essential items), 12% (standard goods), 18% (most goods and services), and 28% (luxury items). Some items like fresh vegetables and milk are exempt (0%).

Who needs to register for GST?

Businesses with annual turnover exceeding ₹40 lakh (goods) or ₹20 lakh (services) must register. Registration is also mandatory for e-commerce operators, inter-state suppliers, and those under the reverse charge mechanism.

Can I claim Input Tax Credit (ITC)?

Yes, registered businesses can claim ITC on GST paid on purchases used for business purposes. ITC cannot be claimed for goods used for personal consumption or exempt supplies.