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What is GST?
Goods and Services Tax (GST) is India's unified indirect tax that replaced VAT, service tax, excise duty, and a host of other cascading state and central levies. Rolled out on 1 July 2017, GST is charged on the supply of goods and services and is currently levied under four main slabs — 5%, 12%, 18%, and 28% — with a 0% (nil-rated) category for essentials. This calculator lets you either add GST to a base price or remove GST from a price that already includes tax, and shows the CGST/SGST split for the transaction.
How the Calculation Works
The tool behaves differently depending on whether your entered amount already includes GST:
GST Amount = Amount × Rate ÷ 100
Total Price = Amount + GST Amount
Remove GST (GST-Inclusive amount):
Original Price = Total × 100 ÷ (100 + Rate)
GST Amount = Total − Original Price
Split (intra-state): CGST = GST Amount ÷ 2, SGST = GST Amount ÷ 2
Worked Example 1 — Adding GST
A wholesaler sells goods worth ₹10,000 (exclusive of tax) at the 18% slab:
- GST Amount = 10,000 × 18 ÷ 100 = ₹1,800
- Total Invoice Value = 10,000 + 1,800 = ₹11,800
- If sold within the same state: CGST = ₹900 and SGST = ₹900 (9% each)
Worked Example 2 — Removing GST (Reverse Calculation)
A retailer receives an invoice showing a final price of ₹23,600, which already includes 18% GST, and needs to know the original (pre-tax) value:
- Original Price = 23,600 × 100 ÷ 118 = ₹20,000
- GST Amount = 23,600 − 20,000 = ₹3,600
- CGST = ₹1,800 and SGST = ₹1,800 for an intra-state sale
GST Slabs in India
| Slab | Typical Items |
|---|---|
| 0% | Fresh milk, eggs, fresh produce, unbranded food grains, printed books |
| 5% | Packaged food staples, footwear under ₹1,000, economy transport, life-saving drugs |
| 12% | Processed food, business-class air tickets, some mobile phones, ayurvedic medicines |
| 18% | Most services, electronics, software/SaaS, AC restaurants, financial services |
| 28% | Luxury cars, tobacco, aerated drinks, high-end consumer durables |
CGST, SGST, and IGST — What's the Difference?
When goods or services are sold within the same state, GST is split equally between CGST (Central GST, goes to the union government) and SGST (State GST, goes to the state government) — each at half the total rate, as shown in the examples above. When a sale crosses state lines, the full rate is instead charged as a single IGST (Integrated GST), which is later apportioned between the centre and the destination state. Our calculator always shows the CGST/SGST breakdown, which applies for intra-state billing; for an inter-state invoice, the same total GST amount would appear entirely as IGST instead.
How to Use This GST Calculator
- Enter the amount — either the base (pre-tax) price or a total that already includes GST.
- Select the applicable GST rate: 5%, 12%, 18%, or 28%.
- Choose GST Exclusive if you want to add tax, or GST Inclusive if you want to extract the tax already built into the price.
- Click Calculate to instantly view the GST amount, CGST, SGST, and the final/original price.
Working out a plain percentage rather than a tax slab? Try the Percentage Calculator. Calculating a sale discount before tax is added? See the Discount Calculator.
📅 Last reviewed: July 2026 · Formulas verified against RBI/SEBI/IT Dept guidelines.