GST Calculator
Calculate GST amounts instantly. Add GST to a base price, extract GST from a total price, or find the GST component alone — three modes for every invoice, estimate, and tax filing.
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GST Amount
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How GST Calculator Works
What is GST in India?
Goods and Services Tax (GST) is India's unified indirect tax system introduced on 1 July 2017, replacing a complex web of central and state levies. It is a multi-stage, destination-based tax applied at each point of value addition. For consumers and businesses, GST is expressed as a percentage of the price of goods or services.
GST in India is administered under four tax slabs — 5%, 12%, 18%, and 28% — plus a 0% slab for essential goods. Some goods attract a 3% rate (gold, silver) or special cess on top of the base rate.
GST-Exclusive vs GST-Inclusive Pricing
The two most common GST pricing scenarios are:
- GST-Exclusive (Base Price): The listed price does not include GST. GST is added on top. This is common in B2B invoices and wholesale pricing.
- GST-Inclusive (MRP / Total Price): The listed price already includes GST. You need to reverse-calculate the tax component. This is common in retail and e-commerce where the price tag shows the final amount.
GST Calculation Formulas
1. GST Exclusive — Adding GST to a Base Price
GST Amount = Base Price × GST Rate ÷ 100
Total Price = Base Price + GST Amount
Example: Base price ₹1,000 at 18% GST:
GST = 1000 × 18 ÷ 100 = ₹180
Total = 1000 + 180 = ₹1,180
2. GST Inclusive — Extracting GST from a Total Price
Base Price = Total Price ÷ (1 + GST Rate ÷ 100)
GST Amount = Total Price − Base Price
Example: Total price ₹1,180 at 18% GST:
Base = 1180 ÷ 1.18 = ₹1,000
GST = 1180 − 1000 = ₹180
3. GST Amount Only
Use this when you need the GST component alone (for invoice line items or tax reports):
GST Amount = Base Price × GST Rate ÷ 100
GST Slab Rates in India
| Rate | Category Examples |
|---|---|
| 0% | Essential food items (fresh vegetables, milk, eggs), books, newspapers |
| 3% | Gold, silver, precious metals and stones |
| 5% | Packed food items, economy hotels, transport services, medicines |
| 12% | Processed food, computers, business-class air travel |
| 18% | Most services, electronics, IT services, restaurants (AC), hotels |
| 28% | Luxury goods, automobiles, aerated drinks, casinos, tobacco products |
CGST, SGST, and IGST
Indian GST is split depending on the transaction type:
- Intra-state sales: GST is split equally between CGST (Central GST) and SGST (State GST). For 18% GST, CGST = 9% and SGST = 9%.
- Inter-state sales: The full rate applies as IGST (Integrated GST). For 18% GST, IGST = 18%.
Our calculator computes the combined GST amount. Divide by 2 for CGST/SGST split.
Accuracy & Sources
Last reviewed: July 2026. Formula source: GST Council of India — tax slab rates and calculation methodology. All calculations run in your browser. No data is sent to any server.
Frequently Asked Questions
GST (Goods and Services Tax) is India's unified indirect tax on the supply of goods and services, introduced on 1 July 2017. It is calculated as a percentage of the base price. For a GST-exclusive price, use: GST Amount = Base Price × GST Rate ÷ 100. For example, 18% GST on ₹500 = ₹500 × 18 ÷ 100 = ₹90. The total payable is ₹590.
GST-exclusive pricing means the listed price does not include GST — tax is added on top. GST-inclusive pricing (such as MRP on retail products) means the listed price already includes GST. To find the pre-GST base price from an inclusive price: Base = Total ÷ (1 + GST Rate ÷ 100). For example, ₹590 at 18% GST: Base = 590 ÷ 1.18 = ₹500.
Use the GST Inclusive tab. Enter the total price (MRP) and the GST rate. The formula is: Base Price = Total Price ÷ (1 + GST Rate ÷ 100). For ₹1,180 at 18% GST: Base = 1180 ÷ 1.18 = ₹1,000, and GST = ₹180. This is called reverse GST calculation.
India has five main GST slabs: 0% (essential items like fresh food, books), 5% (packed food, medicines, transport), 12% (processed food, computers), 18% (most services, electronics, restaurants), and 28% (luxury goods, automobiles, tobacco). A special 3% rate applies to gold and silver. Some goods attract additional cess on top of the base rate.
Select 'GST Exclusive' mode, enter your base price, and choose 18% from the rate selector. Alternatively, use the formula: GST Amount = Price × 0.18, and Total = Price × 1.18. For ₹2,000: GST = ₹360, Total = ₹2,360.
For intra-state transactions (buyer and seller in the same state), GST is split equally between CGST (Central GST) and SGST (State GST). At 18%, each is 9%. For inter-state transactions, the full rate applies as IGST (Integrated GST). Our calculator gives you the combined total; divide the GST amount equally for CGST/SGST splits.
Yes. Select 'Custom rate' from the GST Rate dropdown and enter any rate between 0 and 100. This is useful for cess-inclusive calculations, special composite rates, or calculations for other GST jurisdictions. The calculator supports up to two decimal places in the rate.