GST Calculator: CGST, SGST & IGST
India's GST operates on four rate slabs: 0%, 5%, 18%, and 40% following the GST 2.0 reforms effective 22 September 2025 (the 12% and 28% slabs were abolished). For a transaction within a single state, the rate splits equally into CGST and SGST: an 18% GST becomes 9% CGST plus 9% SGST, while 40% becomes 20% CGST plus 20% SGST. For inter-state transactions, the full rate is charged as IGST. Enter any amount above to see the exact breakdown.
Enter the pre-tax bill amount. GST will be added on top.
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How GST is Calculated in India
Goods and Services Tax (GST) is a destination-based, multi-stage consumption tax levied on the supply of goods and services in India. Depending on whether your pricing is pre-tax (exclusive) or post-tax (inclusive), GST is calculated using two standard mathematical formulas:
Total Amount = Base Amount + GST Amount
Used when billing clients with an agreed base cost plus applicable government taxes.
GST Amount = Total Amount - Base Amount
Used when extracting pre-tax costs and recoverable input tax from MRP retail receipts.
CGST vs SGST vs IGST: What is the Difference?
Under the Indian GST framework, taxes are split depending on whether the seller and buyer are registered in the same state (Intra-State) or across state borders (Inter-State).
| Tax Component | Full Name | Applicability | Rate Allocation (e.g. 18% GST) |
|---|---|---|---|
| CGST | Central Goods and Services Tax | Intra-State transactions (within same state) | 9% (50% share to Central Govt) |
| SGST / UTGST | State / Union Territory GST | Intra-State transactions (within same state) | 9% (50% share to State Govt) |
| IGST | Integrated Goods and Services Tax | Inter-State transactions & Imports | 18% (100% collected by Centre & shared) |
The Current Indian GST Rate Slabs (GST 2.0)
Under the revised GST 2.0 framework effective 22 September 2025, goods and commercial services are categorised into four rationalised tax slabs:
| Slab | Classification | Common Examples | Intra-State Split |
|---|---|---|---|
| 0% | Nil / Exempt | Fresh milk, unbranded grains, fresh fruit and vegetables, bread, salt, curd | 0% + 0% |
| 5% | Essentials & mass consumption | Packaged food, tea, coffee, edible oil, railway and economy air travel, most items moved down from the old 12% slab | 2.5% CGST + 2.5% SGST |
| 18% | Standard rate (most common) | Software and SaaS, IT services, restaurant dining, telecom, hotel rooms, most items moved down from the old 28% slab | 9% CGST + 9% SGST |
| 40% | Sin & luxury goods | Tobacco products, pan masala, aerated drinks, select high-end luxury goods | 20% CGST + 20% SGST |
What happened to the 12% and 28% GST slabs?
The 12% and 28% GST slabs were abolished on 22 September 2025 following the 56th GST Council meeting. Goods and services previously taxed at 12% were moved to either 5% or 18%. Most items previously at 28% were moved to 18%. A new 40% slab was introduced for sin and luxury goods such as tobacco, pan masala and aerated drinks. India now operates a simplified structure of 0%, 5%, 18% and 40%.
How to Remove GST from a Total (Worked Reverse GST Example)
Suppose you received a hotel or restaurant bill with a final paid total of ₹1,180 at an 18% GST slab. To calculate the pre-tax base expense for your company reimbursement:
Note: To verify the vendor's registration before claiming Input Tax Credit, you can check their 15-digit code using our free GSTIN Validator tool.
Frequently Asked Questions
Common questions about GST calculations, tax slabs, and expense claiming rules in India.
Q1.How do I calculate GST on an amount?
Multiply the base amount by the GST rate. For example, for ₹1,000 at 18% GST, the GST amount is (1000 × 18) / 100 = ₹180, and the total gross amount is ₹1,180.
Q2.How do I remove GST from a total amount?
Divide the total gross amount by (1 + rate/100). For example, a ₹1,180 total inclusive of 18% GST gives a base amount of ₹1,180 / 1.18 = ₹1,000, and the GST portion is ₹180.
Q3.What is the difference between CGST, SGST and IGST?
CGST (Central GST) and SGST (State GST) apply to intra-state transactions within a single state, splitting the tax rate equally between the central and state governments (e.g. 18% splits into 9% CGST + 9% SGST, 40% splits into 20% CGST + 20% SGST). IGST (Integrated GST) applies to inter-state transactions between two different states and is charged at the full rate (18% or 40%).
Q4.What are the GST slabs in India?
India operates four GST rate slabs: 0% (exempt essentials), 5% (mass consumption goods), 18% (standard rate covering most goods and services), and 40% (sin and luxury goods). The 12% and 28% slabs were abolished on 22 September 2025.
Q5.Is 18% GST split as 9% CGST and 9% SGST?
Yes, for intra-state transactions (where the supplier and recipient are in the same state), 18% GST is split exactly into 9% CGST and 9% SGST. For inter-state transactions, it is charged as 18% IGST.
Q6.Do I need a GSTIN to claim GST on a bill?
Yes. To claim Input Tax Credit (ITC) or corporate expense reimbursement with tax recovery, the invoice must carry the supplier's valid 15-character GSTIN. You can check any number using our free GSTIN Validator.
Q7.Are the 12% and 28% GST slabs still valid?
No. Both were abolished effective 22 September 2025. Items previously at 12% moved to 5% or 18%, and most 28% items moved to 18%. Invoices dated before 22 September 2025 still legitimately show the old rates (which you can calculate using our Custom Rate option).
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