CalculatrHow to Calculate GST in India: Formula and Examples
Table of Contents
GST (Goods and Services Tax) was introduced in India on 1 July 2017 as a unified indirect tax on goods and services. It is a tax collected at every stage of the supply chain, with credit for tax paid earlier in the chain. Whether you are a business owner, a freelancer, or a consumer, understanding how GST is calculated is essential.
You can use our 🧾 Free GST Calculator to instantly calculate GST for any amount across all slabs.
What is GST?
GST is a destination-based, multi-stage, comprehensive indirect tax. "Multi-stage" means it is collected at every point in the supply chain — from manufacturer to retailer. "Destination-based" means it is collected in the state where the goods or services are finally consumed, not where they are produced.
GST replaced a complex web of taxes that varied state by state. Before GST, a product could attract different tax rates depending on which state you were in — making business across India unnecessarily complicated. GST brought these under one framework.
GST Slab Rates 2026
Following the 56th GST Council meeting on 3 September 2025, the Council recommended a structure with a standard rate of 18%, a merit rate of 5% and a special rate of 40% for a select few goods and services, effective 22 September 2025 (source: PIB release on the 56th GST Council recommendations). The table gives examples from that release, not a full list. See our GST rates guide for more.
| GST Rate | Examples from the Council release |
|---|---|
| Nil | UHT milk, pre-packaged and labelled paneer (chena), rotis and other Indian breads |
| 5% | Cheese, hair oil, shampoo, toothpaste, toilet soap bars; medicines in general |
| 18% | Air conditioners, cement, televisions, small cars |
| 40% | Sugar-sweetened or flavoured aerated drinks and caffeinated beverages |
The rate for any product depends on its HSN code, and for a service on its SAC code. Notifications can change after the date of the source above, so check the code on gst.gov.in.
How to Calculate GST — Formula
Method 1: Adding GST to a Price (Exclusive GST)
Use this when the price shown does NOT include GST (most B2B invoices).
- GST Amount = Original Price × GST Rate / 100
- Total Price = Original Price + GST Amount
Example: Product costs ₹10,000 + 18% GST
GST = ₹10,000 × 18/100 = ₹1,800
Total = ₹10,000 + ₹1,800 = ₹11,800
Method 2: Removing GST from a Price (Inclusive GST)
Use this when the MRP or price already includes GST (most retail prices).
- Original Price = Inclusive Price ÷ (1 + GST Rate/100)
- GST Amount = Inclusive Price – Original Price
Example: MRP is ₹11,800 inclusive of 18% GST
Original Price = ₹11,800 ÷ 1.18 = ₹10,000
GST = ₹11,800 – ₹10,000 = ₹1,800
CGST vs SGST vs IGST — What's the Difference?
GST is split into three components depending on whether the transaction is within the same state or between two states:
| Component | Full Form | When Applied | Goes To |
|---|---|---|---|
| CGST | Central GST | Intra-state (same state) | Central Government |
| SGST | State GST | Intra-state (same state) | State Government |
| IGST | Integrated GST | Inter-state (different states) + Imports | Centre (then shared) |
Key Rule: For intra-state supply, the GST is split equally between CGST and SGST. For inter-state supply, the full GST is charged as IGST by the Centre.
Example: A Delhi shop sells to a Delhi customer at 18% GST → 9% CGST + 9% SGST
A Delhi shop sells to a Mumbai customer at 18% GST → 18% IGST (no CGST/SGST split)
Real-World GST Calculation Examples
Example 1: Bill with 5% GST (Intra-state)
| Item | Amount |
|---|---|
| Taxable value | ₹2,000 |
| CGST @ 2.5% | ₹50 |
| SGST @ 2.5% | ₹50 |
| Total Bill | ₹2,100 |
Example 2: Purchase with 18% GST
| Item | Amount |
|---|---|
| Base price | ₹15,000 |
| GST @ 18% | ₹2,700 |
| Final Price | ₹17,700 |
Example 3: Invoice with 18% IGST (Inter-state)
| Item | Amount |
|---|---|
| Taxable value | ₹50,000 |
| IGST @ 18% | ₹9,000 |
| Total Invoice | ₹59,000 |
Common GST Calculation Mistakes to Avoid
- Applying wrong GST rate: Always verify the HSN code or SAC code for the specific product/service before applying a rate.
- Forgetting cess: Some goods, such as pan masala and tobacco products, attract compensation cess on top of GST per the Council release. Factor it into the total tax on these items.
- Using wrong GST type: Billing CGST+SGST on an inter-state transaction (should be IGST) is a common error. Check the place of supply rules.
- Reverse charge confusion: For certain notified supplies the buyer, not the supplier, pays the GST. This is called Reverse Charge Mechanism (RCM). Check whether it applies to your case.
Frequently Asked Questions
Q: Can I claim GST paid as a business expense?
A GST-registered business can generally claim Input Tax Credit on GST paid on business purchases, subject to conditions. Check the current rules on gst.gov.in. If you are not registered, the GST paid is part of your cost.
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