GST Calculator India
Calculate GST, reverse GST and full tax breakdown
Enter an amount and GST rate to see the full tax breakdown
This calculator supports all Indian GST slabs — 0%, 5%, 12%, 18%, 28% — and shows CGST/SGST splits for intra-state transactions alongside the IGST amount.
Every Indian business owner, freelancer, and consumer deals with GST on a daily basis. A freelance developer billing ₹85,000 for a web project needs to know whether to charge ₹1,00,300 or ₹85,000 to their client. A shopkeeper in Rajasthan buying goods from a Mumbai supplier needs to know the IGST breakdown on their purchase order. A restaurant customer in Bengaluru wants to check whether the 18% GST on their ₹2,500 bill is correct or whether the restaurant has charged the wrong slab. And a small business owner who received an ₹11,800 invoice wants to know how much of that was the actual service charge and how much was tax.
This GST calculator India handles all of these situations in one place. You can add GST to a base price to find the total invoice amount, or remove GST from a total to find what the original price was before tax. It supports all five Indian GST slabs at 0%, 5%, 12%, 18%, and 28% plus any custom rate between 0 and 100%. It shows the CGST and SGST split for intra-state transactions and the IGST amount for inter-state ones. And it generates a comparison table showing what the same amount would cost under every GST slab side by side.
Why This GST Calculator Is More Useful Than a Basic Online Tool
Most GST calculators in India do one thing: multiply a number by 1.18 or divide by 1.18. That is useful for a quick check but does not answer the complete set of questions that arise around Indian GST in real business and personal finance situations. Here is what this calculator does differently.
Reverse GST calculator — extract base price from GST-inclusive total
Most calculators only add GST. This one also removes it. When you receive an invoice showing ₹11,800 total at 18% GST and need to know what the base service amount was, the reverse calculation gives you ₹10,000 instantly. The formula is different from simply subtracting 18% — you divide by 1.18, not subtract 18% of the total. This tool applies the correct formula so you do not undercount or overcount the base amount on your books or returns.
CGST and SGST split for intra-state, IGST for inter-state
Whether GST goes to the state government, the central government, or both depends entirely on whether the transaction is within the same state or crosses state lines. For intra-state transactions, GST is split equally as CGST and SGST. At 18%, that is 9% CGST and 9% SGST. For inter-state transactions, the full 18% goes as IGST to the Centre which then settles with the destination state. This calculator shows both breakdowns so you can fill your GST invoice correctly without having to manually split the numbers.
All-slab comparison table generated automatically
After every calculation, a comparison table shows what the same base amount would cost under every GST slab from 0% to 28%. On a ₹10,000 base, this shows ₹10,000 at 0%, ₹10,500 at 5%, ₹11,200 at 12%, ₹11,800 at 18%, and ₹12,800 at 28% in one glance. This is genuinely useful when you are unsure which slab applies to your product and want to see the financial impact of each option before confirming with your CA.
Visual breakdown with doughnut chart and slab bar chart
Two charts appear with every calculation. The first is a doughnut chart showing base amount versus GST (split into CGST and SGST if intra-state). The second is a bar chart comparing the GST amount at every slab for your entered base price, with your selected slab highlighted in darker colour. These visuals make it easier to explain GST breakdowns to clients, customers, or team members who are not accountants.
GST as percentage of total amount clearly displayed
Many people confuse the GST rate with the percentage of the total invoice that is tax. At 18% GST, the tax component of the total invoice is actually 15.25%, not 18% — because 18% is applied to the base, not the final total. The progress bar shows this correct percentage explicitly, which helps when you need to split a GST-inclusive amount into base and tax for accounting entries.
Custom rate support for special GST scenarios
Not all products fit the standard five slabs. Certain goods attract cess on top of the standard rate. Some services have composite rates. The custom rate input accepts any value between 0 and 100 so you can calculate GST for non-standard scenarios like a 3% rate on gold jewellery, or a combined 28% plus cess scenario for tobacco products, without switching tools.
The GST Formulas This Calculator Uses
These are the exact formulas applied by this calculator. Every result you see in the output is computed from these formulas with no rounding shortcuts except at the final display step.
GST Amount = Base Price × (GST Rate ÷ 100)
Total Amount = Base Price + GST Amount
- Example: Base ₹10,000 at 18% GST
- GST = ₹10,000 × (18 ÷ 100) = ₹1,800
- Total = ₹10,000 + ₹1,800 = ₹11,800
- CGST (intra-state) = ₹1,800 ÷ 2 = ₹900
- SGST (intra-state) = ₹1,800 ÷ 2 = ₹900
- IGST (inter-state) = ₹1,800 (full amount, no split)
This is the standard formula used for generating GST invoices. The GST rate is applied to the exclusive (pre-tax) price. The total on your invoice should equal base plus GST, not base plus a percentage of the total.
Base Price = Total Amount × 100 ÷ (100 + GST Rate)
GST Amount = Total Amount − Base Price
- Example: Total ₹11,800, GST rate 18%
- Base = ₹11,800 × 100 ÷ (100 + 18) = ₹11,800 × 100 ÷ 118 = ₹10,000
- GST = ₹11,800 − ₹10,000 = ₹1,800
- CGST = ₹900, SGST = ₹900 (for intra-state)
This is the most commonly misunderstood GST calculation. A frequent mistake is to subtract 18% directly from the total: ₹11,800 × 18% = ₹2,124, which is wrong. The correct method divides by (1 + rate). The reason: ₹11,800 is 118% of the base, not 100%. To find 100%, you divide by 1.18. Enter any GST-inclusive total in the "Remove GST" mode and the calculator applies this correct formula automatically.
CGST = Total GST ÷ 2
SGST = Total GST ÷ 2
CGST Rate = GST Rate ÷ 2 | SGST Rate = GST Rate ÷ 2
- At 18% GST (intra-state): CGST = 9%, SGST = 9%
- At 12% GST (intra-state): CGST = 6%, SGST = 6%
- At 5% GST (intra-state): CGST = 2.5%, SGST = 2.5%
- At 28% GST (intra-state): CGST = 14%, SGST = 14%
CGST and SGST are always equal halves of the total GST for intra-state transactions. Both must be shown as separate line items on a GST invoice. If you charge CGST 9% and SGST 9% on a ₹10,000 invoice, the invoice shows three lines: base ₹10,000, CGST ₹900, SGST ₹900, total ₹11,800. IGST is never split and never coexists with CGST or SGST on the same invoice.
GST Share of Total = GST Rate ÷ (100 + GST Rate) × 100
- At 5%: GST is 4.76% of the total invoice amount
- At 12%: GST is 10.71% of the total invoice amount
- At 18%: GST is 15.25% of the total invoice amount
- At 28%: GST is 21.88% of the total invoice amount
This number matters for accounting entries. If you receive a ₹11,800 invoice and need to separate it into base and tax for journal entries without a GST-split invoice, you know 15.25% of the total is GST. Multiply ₹11,800 by 15.25% to get ₹1,799.50 (approximately ₹1,800 after rounding). This saves the manual back-calculation step.
Real Examples: Exact Results From This Calculator
Every number in these examples comes directly from this calculator. Enter the same inputs and the output will match exactly.
Mode: Add GST | Amount: ₹85,000 | Rate: 18% | Split: CGST + SGST
- Base Amount: ₹85,000.00
- Total GST (18%): ₹15,300.00
- CGST (9%): ₹7,650.00
- SGST (9%): ₹7,650.00
- Total Invoice Amount: ₹1,00,300.00
- GST as % of total: 15.25%
This is the most common scenario for Indian freelancers and IT service providers. If you are a GST-registered business providing services to a client in the same state, your invoice shows base ₹85,000, CGST ₹7,650, SGST ₹7,650, and total ₹1,00,300. If the client is in a different state, replace CGST and SGST with IGST ₹15,300. The GST-registered client can claim input tax credit on this GST amount, so the effective cost to them is ₹85,000.
Mode: Remove GST | Amount: ₹11,800 | Rate: 18%
- Total Invoice Amount: ₹11,800.00
- Base Price (ex-GST): ₹10,000.00
- GST Amount: ₹1,800.00
- CGST: ₹900.00 | SGST: ₹900.00
- GST as % of total: 15.25%
This situation comes up constantly for business owners reconciling purchase invoices. If you received a bill for ₹11,800 and need to separate the base and GST for your accounting software or GST return, the base is ₹10,000 and the tax is ₹1,800. Do not subtract 18% from ₹11,800 directly — that gives ₹2,124 which is wrong. The correct base is always calculated by dividing by 1.18.
Mode: Add GST | Amount: ₹2,500 | Rate: 5% (non-AC) and 18% (AC restaurant)
- Non-AC Restaurant at 5%: GST ₹125.00 | Total ₹2,625.00 | CGST ₹62.50 | SGST ₹62.50
- AC Restaurant at 18%: GST ₹450.00 | Total ₹2,950.00 | CGST ₹225.00 | SGST ₹225.00
- Difference between slabs: ₹325.00 more tax at an AC restaurant
This comparison answers one of the most common questions Indian consumers ask: why does eating at an AC restaurant cost so much more in GST? On a ₹2,500 food order, the difference between a non-AC restaurant (5% GST) and an AC restaurant (18% GST) is ₹325 in additional tax. Over a year of weekly lunches, that adds up to ₹16,900 in extra GST from choosing AC dining. The slab comparison table in the calculator shows all five slabs for your amount at once so you never need to run separate calculations.
Mode: Remove GST | Amount: ₹1,05,000 | Rate: 5%
- Total Bill: ₹1,05,000.00
- Base Price of Medicines: ₹1,00,000.00
- GST Amount (5%): ₹5,000.00
- CGST (2.5%): ₹2,500.00 | SGST (2.5%): ₹2,500.00
Most life-saving drugs and essential medicines attract 5% GST. If you paid ₹1,05,000 at a pharmacy and need to know the pre-tax value for insurance reimbursement or business expense claims, the base amount is exactly ₹1,00,000 and the GST was ₹5,000. Use this mode whenever you receive a GST-inclusive bill and need to record the components separately.
India's GST Slabs in 2026: What Falls Where
India's GST structure uses five main tax slabs. Knowing which slab your product or service falls in saves you from either overcharging your customers or underreporting to the government. The GST Council periodically reviews slab classifications, so always verify with the official CBIC HSN/SAC code lookup for any product you are unsure about.
| GST Slab | What It Covers | GST on ₹10,000 Base | Total on ₹10,000 Base | GST Share of Total |
|---|---|---|---|---|
| 0% (Exempt) | Fresh fruits, vegetables, milk, eggs, bread, unbranded rice and wheat, books, newspapers, healthcare services, educational services | ₹0.00 | ₹10,000.00 | 0% |
| 5% | Packed foods, coffee and tea, edible oils, life-saving drugs, economy air travel, household goods like sugar and spices, non-AC restaurant food | ₹500.00 | ₹10,500.00 | 4.76% |
| 12% | Processed foods, smartphones, business-class air travel, hotels between ₹1,000 and ₹7,500 per night, construction services for affordable housing | ₹1,200.00 | ₹11,200.00 | 10.71% |
| 18% | Most manufactured goods, IT and software services, telecom services, financial services, AC restaurants, hotels above ₹7,500 per night, most professional services | ₹1,800.00 | ₹11,800.00 | 15.25% |
| 28% | Cars and two-wheelers, tobacco and pan masala, aerated drinks and beverages, high-end electronics, luxury hotels, casinos, five-star hotel services | ₹2,800.00 | ₹12,800.00 | 21.88% |
GST slab classifications change periodically based on GST Council decisions. The table above reflects the structure as of 2026 but specific products within each category may be reclassified. Always verify your product's HSN code and the applicable GST rate on the official CBIC website before raising invoices. For official GST rate verification, visit CBIC's official portal at cbic.gov.in where the full GST rate schedule is publicly available. Wrongly charging a higher slab rate means your customer overpays and you may face compliance issues.
How to Use This GST Calculator: Step by Step
Step 1: Choose your calculation mode
Select "Add GST to Amount" if you have a base price and want to find the total. This is the mode for generating invoice amounts, quoting clients, or calculating what you will charge as a GST-registered business. Select "Remove GST from Amount" if you have a GST-inclusive total and want to find the base price and tax amount separately. This is the mode for reconciling invoices you have received, finding the original price of a product, or separating base and tax for accounting entries.
Step 2: Enter your amount
In Add mode, enter the base price before tax. In Remove mode, enter the total amount that already includes GST. The label in the form changes to make it clear which one to enter. Decimal values are accepted for precise invoice calculations.
Step 3: Select the GST slab
Click the slab button for 0%, 5%, 12%, 18%, or 28%. If your product attracts a special rate like 3% for gold jewellery or a composite rate, type it directly in the custom rate field. The calculator accepts any rate between 0 and 100. If you are unsure which slab your product falls under, the slab comparison table in the results shows all five standard options simultaneously so you can see the financial impact of each before confirming the correct rate with your tax advisor or the CBIC lookup tool.
Step 4: Choose IGST or CGST plus SGST
Select IGST if your transaction crosses state lines — for example, a Mumbai supplier billing a Bengaluru client, or imports. Select CGST plus SGST if the buyer and seller are in the same state. The choice determines how the tax amount is split between the Centre and the state. The GST amount itself is identical either way. Only the component split changes.
Step 5: Read the results and the slab comparison table
The primary card shows the key result — total in Add mode, base in Remove mode. The metric grid below shows base, GST, total, and effective rate. The component split section shows either IGST alone or CGST plus SGST amounts with their individual rates. The comparison table at the bottom shows what the same transaction would look like under every standard GST slab. For any GST calculations involving your personal income tax planning — such as GST on professional income affecting your total taxable income — use our income tax calculator alongside this tool to understand the combined tax impact.
IGST vs CGST vs SGST: Which Applies When and Why It Matters on Your Invoice
This is the most common source of confusion when GST-registered businesses raise invoices. The three terms — IGST, CGST, and SGST — all refer to the same GST amount, just split differently depending on whether the transaction crosses state lines.
When the supplier and buyer are in the same state, GST is collected as two equal halves. CGST (Central Goods and Services Tax) goes to the Government of India. SGST (State Goods and Services Tax) goes to the state government where the supply takes place.
On an ₹85,000 IT invoice at 18% GST within Maharashtra: CGST = ₹7,650 (to Centre) and SGST = ₹7,650 (to Maharashtra government). Both appear as separate line items on the invoice. Your client sees CGST 9% and SGST 9%, each showing the rupee amount.
Invoice requirement: Both CGST and SGST must be shown as separate line items. You cannot show a combined "GST 18%" on an intra-state invoice. Most accounting software handles this automatically when you select the buyer's state.
When the supplier and buyer are in different states, or for imports into India, the full GST is collected as IGST (Integrated Goods and Services Tax) by the Central Government. The Centre then settles the state's share with the destination state based on the place of supply rules.
On the same ₹85,000 IT invoice from a Mumbai company to a Bengaluru client: IGST = ₹15,300 (full amount to Centre). No CGST or SGST appears on this invoice. The Bengaluru client can claim ITC on this IGST against their own GST liability.
Common mistake: charging CGST plus SGST on an inter-state invoice. This is a GST compliance error. If your client is in a different state, always select IGST. The total GST amount is identical but the wrong split creates problems during GST return filing and ITC claims for your client.
UTGST for Union Territories: For supplies to Union Territories without a legislature (Chandigarh, Dadra and Nagar Haveli, Daman and Diu, Lakshadweep, and Andaman and Nicobar Islands), the state portion is called UTGST instead of SGST. The calculation is identical to SGST. This calculator labels it as SGST/UTGST in the results. For transactions involving Delhi, Puducherry, or Jammu and Kashmir (Union Territories with a legislature), normal SGST rules apply.
Frequently Asked Questions
Disclaimer This calculator is for educational and reference purposes only. It does not constitute tax advice. GST compliance requirements, slab classifications, and applicable rates vary by product, service, business type, and jurisdiction. For GST registration, filing, and advisory, consult a qualified CA or GST practitioner. Fintool Baba is not responsible for any errors in GST invoicing or filing arising from use of this tool. For income tax calculations on your professional income including GST turnover impact, use our income tax calculator. To understand your complete monthly cash flow including GST obligations, use our expense planner.