GST Calculator India: How to Calculate GST Online (2026 Guide)
📅 May 2026⏱ 10 min read✍️ ToolLoom Editorial
GST replaced over a dozen indirect taxes in India in 2017. Yet for millions of business owners, freelancers, and consumers, the basics of how to calculate it — add it, remove it, split it into CGST and SGST — remain unclear. This guide covers everything with plain-language explanations and worked examples.
GST (Goods and Services Tax) is a destination-based, multi-stage tax levied on the supply of goods and services in India. Introduced on 1st July 2017, it replaced a complex web of central and state taxes including VAT, service tax, excise duty, CST, and several others — creating a single unified indirect tax system.
GST is collected at every stage of the supply chain, but businesses can claim credit for the GST they already paid on inputs (Input Tax Credit). This means only the final consumer bears the tax burden — businesses in the middle of the chain are essentially pass-throughs.
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GST is consumption-based: Revenue goes to the state where the goods or services are consumed — not where they are produced. This was a fundamental shift from the previous system and is why the "destination principle" matters for understanding CGST, SGST, and IGST.
GST Slabs in India (2026)
India uses a four-tier GST rate structure, with an additional exempt category for essential goods. Here are the current slabs:
0%
Exempt
Fresh vegetables, milk, eggs, bread, public health services, education
GST rates change periodically. The GST Council meets regularly and revises rates on specific goods and services. Always verify the current rate for your specific item or service on the official GST Council website or with a CA before invoicing.
How to Add GST to a Price
This is the most common calculation — you know your base price (before tax) and need to find the GST amount and total invoice value.
Add GST Formula
GST Amount = Base Price × (GST Rate ÷ 100)
Total Price = Base Price + GST Amount
When you know the total price including GST and need to find the original base price — for example, when working backwards from an MRP or a GST-inclusive quote.
Remove GST Formula
Base Price = Total (GST Inclusive) ÷ (1 + GST Rate ÷ 100)
GST Amount = Total − Base Price
📌 Example: MRP = ₹1,180 (18% GST inclusive)
Base Price = ₹1,180 ÷ 1.18 = ₹1,000
GST Amount = ₹1,180 − ₹1,000 = ₹180
✅ Base Price = ₹1,000 | GST = ₹180 | Total = ₹1,180
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The most common mistake: Never calculate GST by applying the rate to the GST-inclusive price. 18% of ₹1,180 = ₹212.40 — which is WRONG. The correct answer is ₹180. Always divide by (1 + rate) first to get the base, then subtract.
Quick reference divisors for removing GST
5% GST: Divide total by 1.05
12% GST: Divide total by 1.12
18% GST: Divide total by 1.18
28% GST: Divide total by 1.28
CGST vs SGST vs IGST — The Difference Explained
GST in India is split between the Central Government and State Governments. How it is split depends on whether the transaction is within one state or across state borders.
CGST — Central GST
Half of GST rate
Collected by the Central Government on intra-state transactions. For 18% GST: CGST = 9%. Goes to Union Government treasury.
SGST — State GST
Half of GST rate
Collected by the State Government on intra-state transactions. For 18% GST: SGST = 9%. Goes to the state where the supply occurs.
IGST — Integrated GST
Full GST rate
Applied on inter-state transactions and imports. For 18% GST: IGST = 18%. Collected by Centre, then shared with destination state.
UTGST — Union Territory GST
Half of GST rate
Replaces SGST for transactions within Union Territories (Delhi, Chandigarh, Puducherry, Andaman etc.) without state legislature.
Transaction Type
Tax Applied
Example
Seller and buyer in same state
CGST + SGST
Delhi seller → Delhi buyer: CGST 9% + SGST 9%
Seller and buyer in different states
IGST
Delhi seller → Mumbai buyer: IGST 18%
Seller in India, buyer outside India (export)
Zero-rated (0%)
Bangalore developer → US client: 0% GST
Import into India
IGST + Customs
Amazon US → Indian buyer: IGST + customs duty
Supply to Union Territory
CGST + UTGST
Mumbai seller → Puducherry buyer: CGST + UTGST
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The total GST amount is always the same — whether it is shown as CGST+SGST or IGST. An 18% GST transaction always costs the buyer the same 18% extra. The split only affects which government account the money goes to — it has no impact on the buyer's total cost.
GST Rates on Common Goods and Services (2026)
Item / Service
GST Rate
Notes
Fresh vegetables, fruits
0%
Exempt — no GST
Milk, eggs, bread
0%
Exempt — no GST
Packaged food (branded)
5%
Pre-packaged and labelled
Tea, coffee (branded)
5%
—
Medicines (most)
5%
Life-saving drugs may be exempt
Restaurant (all — AC and non-AC)
5%
No ITC available (post-2019 revision)
Economy airfare
5%
Business class: 12%
Mobile phones
12%
Revised from 18% in March 2020
Computers, laptops
18%
—
IT / software services
18%
SAC 998314 and related
Health insurance premium
18%
Charged on full premium amount
Term life insurance
18%
—
Home loan processing fee
18%
On the fee amount, not loan principal
Private coaching / tuition
18%
Schools and colleges are exempt
Gold jewellery
3%
Making charges attract 5% GST separately
Petrol / diesel
Outside GST
Taxed under central excise + state VAT
Cars (small petrol under 1200cc)
28% + 1% cess
Effective rate: 29%
SUVs (over 1500cc engine, over 4m)
28% + 22% cess
Effective rate: 50%
Tobacco products
28% + cess
Cess varies by product type
Online gaming (real money)
28%
On full face value of bets since Oct 2023
5 Common GST Calculation Mistakes
Mistake 1 — Applying GST on a GST-inclusive amount
GST is always calculated on the base price — never on the GST-inclusive total. The divisor method (÷ 1.18 for 18%) is the only correct way to extract GST from an inclusive price.
Mistake 2 — Charging CGST+SGST on inter-state invoices
✓ Right: IGST 18% (single integrated tax for inter-state)
The buyer's location determines the tax type. Same state = CGST + SGST. Different states = IGST. Using the wrong type creates compliance issues and affects Input Tax Credit for the buyer.
Mistake 3 — Adding GST on top of MRP
✗ Wrong: MRP ₹118 + 18% GST = ₹139.24
✓ Right: MRP ₹118 already includes GST. Base = ₹100, GST = ₹18.
MRP (Maximum Retail Price) in India is always GST-inclusive. Never add GST on top of an MRP. Retailers cannot charge above MRP regardless of GST rate.
Mistake 4 — Using wrong GST rate for the transaction
✗ Wrong: Charging 18% GST on a restaurant bill
✓ Right: Restaurant GST is 5% for all types (AC and non-AC) since 2019
GST rates change periodically. The GST Council has revised rates multiple times since 2017. Always verify the current rate for your specific goods or service category — especially for frequently-revised categories like restaurants, textiles, and construction.
Mistake 5 — Charging GST without valid registration
✗ Wrong: Collecting 18% GST on invoices before crossing ₹20L threshold
✓ Right: Only registered GST entities can legally collect GST from customers
If you are not GST registered, you cannot charge or collect GST — even voluntarily. Doing so is illegal. If your turnover crosses ₹20 lakh, you must register within 30 days and only start charging GST from the date of registration.
GST = ₹10,000 × 18% = ₹1,800. Total invoice = ₹11,800. If the transaction is intra-state: show CGST = ₹900 + SGST = ₹900 separately. If the transaction is inter-state: show IGST = ₹1,800. The total charged to the client is ₹11,800 in both cases.
GST is charged on the product or service being financed — not on the EMI instalment itself. When you buy a phone on EMI, GST on the phone's price is charged upfront (or factored into the loan amount). However, if a lender charges a processing fee or loan origination fee separately, that fee attracts 18% GST. The EMI principal and interest component do not attract GST.
Normally the supplier collects and deposits GST. Under RCM, the buyer becomes liable to pay GST directly to the government — the supplier does not charge it. RCM applies in specific situations: purchases from unregistered suppliers in notified categories, importing services from abroad, or services specifically notified by the GST Council (like GTA services, advocate fees, director remuneration). Always consult a CA if RCM may apply to your business.
Individual consumers (B2C transactions) generally cannot claim GST refunds. Only registered GST businesses can claim Input Tax Credit. Tourists from abroad who made purchases in India can claim refunds under limited tourist refund schemes at designated airports. Exporters and Special Economic Zone units can claim GST refunds through the GSTN portal for zero-rated supplies.
All restaurants in India — AC and non-AC — now charge 5% GST (no ITC). On a ₹1,000 restaurant bill: GST = ₹1,000 × 5% = ₹50. Total = ₹1,050. Note that restaurants cannot charge 18% GST — that rate was eliminated in 2019. If a restaurant is charging 18%, it is incorrect. Also check whether a service charge has been added — this is separate from GST and legally optional per CCPA guidelines.
Input Tax Credit allows registered GST businesses to deduct the GST they paid on their purchases (inputs) from the GST they collected on their sales (output). For example, a manufacturer who paid ₹18,000 GST on raw materials and collected ₹36,000 GST on finished goods pays only ₹18,000 net to the government. This prevents cascading taxation (tax on tax) and is one of GST's key structural improvements over the old tax system.
No — alcohol for human consumption and five petroleum products (crude oil, natural gas, petrol, diesel, aviation turbine fuel) are currently outside the GST framework. They continue to be taxed under the old system — central excise duty at the federal level and state VAT/sales tax at the state level. This exclusion was a political compromise during GST's rollout and remains a subject of debate.