How GST is Calculated: A Complete Guide
Goods and Services Tax (GST) is applied to most goods and services in India. Understanding how to add or remove GST ensures you're never overcharged or undercharging your customers.
What Is GST?
GST is a value-added tax levied on the supply of goods and services in India (implemented July 2017). It replaced a complex web of central and state taxes including VAT, service tax, and excise duty with a single, unified tax system.
GST is a destination-based tax, meaning it is collected at the point of consumption, not production. The tax is split between the central government (CGST) and state government (SGST), or as IGST for inter-state transactions.
GST Tax Slabs
| Rate | Category | Examples |
|---|---|---|
| 0% | Exempt | Fresh vegetables, milk, eggs, books, newspapers |
| 5% | Essential goods | Cooking oil, sugar, tea, coffee, medicines |
| 12% | Standard goods | Processed food, computers, mobile phones |
| 18% | Standard services | Restaurant (AC), telecom, IT services, hotel rooms (₹2,500–₹7,500) |
| 28% | Luxury/sin goods | Automobiles, tobacco, aerated drinks, luxury hotels |
How to Calculate GST
Adding GST to a price (exclusive → inclusive)
When you know the price before tax and want to find the final price:
Final Price = Original Price + GST Amount
GST = ₹1,000 × 18/100 = ₹180
Final Price = ₹1,000 + ₹180 = ₹1,180
Removing GST from a price (inclusive → exclusive)
When the price includes tax and you want the base price:
GST Amount = Final Price − Original Price
Base Price = ₹1,180 ÷ 1.18 = ₹1,000
GST Paid = ₹1,180 − ₹1,000 = ₹180
CGST, SGST, and IGST — What's the Difference?
Half of GST on intra-state sales. Goes to the central government.
Other half of GST on intra-state sales. Goes to the state government.
Full GST on inter-state sales. Collected by the centre and shared with states.
Common Mistakes in GST Calculation
Frequently Asked Questions
What is GST full form?
GST stands for Goods and Services Tax. It is a comprehensive, indirect tax levied on the supply of goods and services in India, implemented on 1 July 2017, replacing multiple central and state taxes.
Who ultimately pays GST?
The end consumer bears the GST burden. Businesses collect GST on behalf of the government and can claim Input Tax Credit (ITC) for GST paid on their purchases, passing only the net tax to the government.
Which items are exempt from GST in India?
Many essential items are exempt from GST including fresh fruits and vegetables, milk, eggs, unprocessed meat, cereals, salt, books, newspapers, and most educational services. Alcohol for human consumption and petroleum products are kept outside GST.
How do I calculate GST on an invoice?
To add GST: GST Amount = Price × (Rate ÷ 100), Final Price = Price + GST Amount. To remove GST from an inclusive price: Base Price = Inclusive Price ÷ (1 + Rate ÷ 100), GST = Inclusive Price − Base Price.
What is Input Tax Credit (ITC) in GST?
Input Tax Credit allows businesses to deduct the GST they paid on purchases (inputs) from the GST they collected on sales. This prevents cascading taxes — you only pay GST on the value you add, not on the full sale price.
Is GST applicable on exports?
Exports are zero-rated under GST, meaning exporters charge 0% GST on exports and can claim refund of GST paid on inputs used to manufacture the exported goods. This makes Indian exports globally competitive.
Related Calculators
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Add or remove GST at any rate with our free GST calculator. Works for all tax slabs — 5%, 12%, 18%, and 28%.
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