GST Calculator India
Calculate CGST, SGST, and IGST for any amount and rate. Forward and reverse mode for invoicing, billing, and tax compliance.
All calculation runs in your browser. Nothing is sent to any server.
Worked example
A Tamil Nadu retailer sells a phone case for Rs 1,000 to a customer in Tamil Nadu. The phone case is taxed at 18% GST. Since the seller and buyer are in the same state, the transaction is intra-state.
Had the customer been in Karnataka, the same Rs 1,000 sale would carry IGST Rs 180 instead of CGST + SGST, because it crosses state lines. The total to the buyer is identical.
How GST works in India
GST (Goods and Services Tax) is the unified indirect tax that replaced VAT, service tax, excise duty, and several others in 2017. It is a destination-based consumption tax, which means the tax revenue accrues to the state where the goods or services are consumed, not where they were produced.
Three components: CGST, SGST, IGST
CGST (Central) and SGST (State) apply together on sales within a state, each at half the GST rate. IGST applies on inter-state sales and imports, at the full rate. The buyer's place of supply determines which one applies, not the seller.
Five rate slabs
0%, 5%, 12%, 18%, and 28% are the standard slabs. Some categories (gold, rough diamonds, lottery) sit on special rates. A few luxury and sin items attract additional cess on top of 28%, like tobacco and SUVs.
HSN codes determine the rate
Every product has an HSN (Harmonized System of Nomenclature) code; services use SAC codes. The code maps to one of the five GST slabs. Use our free HSN Code Search to find the right code before issuing an invoice.
Input tax credit (ITC) flows through
Registered businesses can claim credit on the GST they paid to suppliers and offset it against the GST they owe on sales. The tax burden ultimately falls on the final consumer; intermediate businesses pass tax through.
GST rate slabs in India
Categories below are illustrative. Last reviewed 6 June 2026. Always verify the latest rate via CBIC GST rate FAQs, official CBIC notifications, or our HSN search tool.
| Slab | Examples | Notes |
|---|---|---|
| 0% | Fresh fruit, milk, unbranded grains, books, education services, healthcare | Essentials and merit goods. Exempt from GST. |
| 5% | Packaged food, edible oils, transport (rail/air economy), small restaurants, footwear < Rs 1,000 | Mass-consumption category. Lowest non-zero slab. |
| 12% | Processed food, ayurvedic medicines, computers, business class travel, butter, ghee | Standard slab for processed and semi-finished goods. |
| 18% | Most services, electronics, telecom, AC restaurants, soap, hair oil, capital goods | Largest revenue slab. Default for most B2B invoices. |
| 28% | Cars, motorcycles, ACs, refrigerators, cement, tobacco, aerated drinks | Luxury and sin goods. Some categories carry additional cess. |
Frequently asked questions
How is GST calculated in India?
GST is calculated as a percentage of the taxable value of goods or services. For an intra-state transaction the rate is split equally between CGST (Central GST) and SGST (State GST). For an inter-state transaction the full rate is charged as IGST (Integrated GST). Formula: Tax = Taxable Value x (Rate / 100). Total = Taxable Value + Tax.
What is the difference between CGST, SGST and IGST?
CGST and SGST are charged together on intra-state sales (buyer and seller in the same state); each is half of the GST rate. IGST is charged on inter-state sales (buyer and seller in different states or on imports); it is the full GST rate as a single component. The buyer's place of supply decides which applies, not the seller.
How do I calculate reverse GST or extract GST from a total amount?
When the price already includes GST, use reverse calculation: Taxable Value = Total / (1 + Rate/100). For example, an 18% GST-inclusive price of Rs 1,180 has a taxable value of 1180 / 1.18 = Rs 1,000, and a tax component of Rs 180. Use the Extract GST mode of the calculator above.
What are the GST rate slabs in India?
Five primary slabs: 0% (essentials), 5% (mass consumption), 12% (processed goods), 18% (most services and electronics), 28% (luxury and sin goods). Some 28% items also attract additional cess. Special rates apply to gold, rough diamonds, and a few categories outside the standard structure.
Is this GST calculator accurate for invoicing?
The math follows the formulas published by CBIC. For invoicing, two extra rules apply: (1) round each tax component to two decimal places, and (2) on a total invoice, round the final amount to the nearest rupee per Section 170 of the CGST Act. This calculator displays both the precise and rounded amounts. For final-mile invoice generation including HSN codes and GST returns, use the OnePlaceHQ Billing module.
Can I calculate GST on multiple line items at once?
This calculator handles a single line item. For multi-line invoices, calculate each line separately and sum the components - that is exactly how the official GSTR-1 line-item table works. The OnePlaceHQ Billing app handles multi-line, GST summary, and GSTR-1 export automatically.
Does this calculator work offline?
Yes. All calculation runs in your browser using JavaScript. No data is sent to any server. Once the page is loaded you can use it without an internet connection.
Is GST calculation different for goods vs services?
The arithmetic is identical. The difference lies in classification: goods use HSN codes to determine the rate, services use SAC codes. Once the rate is known, the same CGST/SGST/IGST formulas apply. Use our HSN Code Search to look up the right rate before calculating.
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