What is GST and how is it calculated?

GST (Goods and Services Tax) is an indirect tax levied on supply of goods and services in India. To calculate GST: GST Amount = (Original Cost × GST%) / 100. For GST inclusive price: Net Price = Total Price × 100 / (100 + GST%). GST rates in India are 0%, 5%, 12%, 18%, and 28%.

What is the difference between CGST, SGST, and IGST?

CGST (Central GST) and SGST (State GST) are levied on intra-state transactions, each being 50% of total GST. IGST (Integrated GST) is levied on inter-state transactions and equals the full GST rate. For example, 18% GST intra-state = 9% CGST + 9% SGST, while inter-state = 18% IGST.

How to calculate reverse GST?

Reverse GST calculation finds the original price from GST-inclusive price. Formula: Original Price = (GST Inclusive Price × 100) / (100 + GST Rate). GST Amount = GST Inclusive Price - Original Price. For example, if final price is ₹1,180 with 18% GST: Original = 1180 × 100 / 118 = ₹1,000, GST = ₹180.

What are the current GST rates in India?

GST rates in India are: 0% (essential items like fresh food), 5% (household necessities), 12% (processed food, computers), 18% (most goods and services), and 28% (luxury items, automobiles). Some items like petroleum, alcohol are outside GST.

Is GST registration mandatory?

GST registration is mandatory if annual turnover exceeds ₹40 lakhs for goods (₹20 lakhs for special category states) or ₹20 lakhs for services. It's also mandatory for inter-state suppliers, e-commerce sellers, and certain specified businesses regardless of turnover.

GST Calculator 2025 - Calculate GST Online (India)

What is GST and How to Calculate It?

GST (Goods and Services Tax) is an indirect tax levied on the supply of goods and services in India. Introduced on July 1, 2017, GST replaced multiple indirect taxes like VAT, Service Tax, and Excise Duty, creating a unified tax system across India.

Our GST calculator helps you instantly calculate GST-inclusive prices, GST-exclusive prices, and reverse GST calculations with detailed CGST, SGST, and IGST breakdowns.

GST Calculation Formulas

Add GST (GST Exclusive to Inclusive)

GST Amount = (Original Price × GST%) / 100
Final Price = Original Price + GST Amount

Example: Product costs ₹1,000 with 18% GST

GST Amount = (1000 × 18) / 100 = ₹180
Final Price = 1000 + 180 = ₹1,180

Remove GST (Reverse GST Calculation)

Original Price = (GST Inclusive Price × 100) / (100 + GST%)
GST Amount = GST Inclusive Price - Original Price

Example: Final price is ₹1,180 with 18% GST

Original Price = (1180 × 100) / (100 + 18) = ₹1,000
GST Amount = 1180 - 1000 = ₹180

Understanding CGST, SGST, and IGST

CGST (Central Goods and Services Tax)

CGST is the tax collected by the Central Government on intra-state sales. It is 50% of the total GST rate.

Example: For 18% GST, CGST = 9%

SGST (State Goods and Services Tax)

SGST is the tax collected by the State Government on intra-state sales. It is also 50% of the total GST rate.

Example: For 18% GST, SGST = 9%

IGST (Integrated Goods and Services Tax)

IGST is levied on inter-state transactions (sales between different states). The full GST amount goes to the Central Government, which then distributes it.

Example: For 18% GST on inter-state sale, IGST = 18%

Quick Comparison

Transaction Type	Tax Components	Example (18% GST)
Intra-State (Within same state)	CGST + SGST	9% CGST + 9% SGST
Inter-State (Between states)	IGST	18% IGST

GST Rates in India (2025)

0% GST (Nil Rate)

Items: Fresh vegetables, fruits, milk, eggs, bread, salt, jaggery, educational services, healthcare services

Rationale: Essential items for daily consumption

5% GST

Items: Household necessities, sugar, tea, coffee, edible oils, coal, medicines, life-saving drugs, transport services

Rationale: Common household items and essential services

12% GST

Items: Processed food, butter, cheese, ghee, computers, mobile phones (up to ₹25,000), business class air tickets

Rationale: Processed goods and mid-range products

18% GST (Most Common)

Items: Most goods and services, IT services, telecom services, financial services, restaurants (non-AC), capital goods, industrial intermediaries

Rationale: Standard rate for majority of goods and services

28% GST

Items: Luxury items, automobiles, AC restaurants, 5-star hotels, aerated drinks, tobacco products, pan masala, cinema tickets (above ₹100)

Rationale: Luxury and sin goods

How to Use the GST Calculator

Choose Calculation Type: Select "Add GST" to calculate final price or "Remove GST" for reverse calculation.
Enter Amount: Input the base price (for Add GST) or final price (for Remove GST).
Select GST Rate: Click on 5%, 12%, 18%, or 28% buttons, or enter a custom rate.
Choose Transaction Type: Check "Inter-State Transaction" if selling to another state (IGST), leave unchecked for same state (CGST+SGST).
View Results: See GST amount, base price, final price, and detailed tax breakdown instantly.
Check Comparison: Review how different GST rates affect the final price.
Preview Invoice: See a professional invoice format with all tax components.

GST Registration: Who Needs It?

Mandatory Registration

Turnover Threshold: Businesses with annual turnover exceeding ₹40 lakhs (₹20 lakhs for special category states) for goods, or ₹20 lakhs for services
Inter-State Suppliers: Any business making inter-state supplies, regardless of turnover
E-commerce Sellers: All sellers on platforms like Amazon, Flipkart
Casual Taxable Persons: Businesses operating temporarily
Reverse Charge Mechanism: Businesses receiving goods/services under RCM
Input Service Distributors: Entities distributing input tax credit
Non-Resident Taxable Persons: Foreign businesses supplying in India

Voluntary Registration

Businesses below the threshold can voluntarily register to:

Claim input tax credit
Expand business to other states
Build credibility with customers
Sell on e-commerce platforms

GST Input Tax Credit (ITC)

What is Input Tax Credit?

Input Tax Credit allows businesses to reduce the GST paid on purchases from the GST collected on sales. This prevents cascading tax effect.

Example of ITC

Scenario: You're a retailer

Purchased goods for ₹10,000 + ₹1,800 GST (18%) = ₹11,800
Sold goods for ₹15,000 + ₹2,700 GST (18%) = ₹17,700
GST Payable: ₹2,700 (collected) - ₹1,800 (paid) = ₹900

Conditions for Claiming ITC

Must possess valid tax invoice
Goods/services received
GST paid to supplier
Supplier has filed GST returns
Your GST returns are filed

Common GST Scenarios and Examples

Scenario 1: Restaurant Bill

Situation: Dining at a non-AC restaurant

Food cost: ₹500
GST: 5% = ₹25
Total bill: ₹525

Scenario 2: Mobile Phone Purchase

Situation: Buying a smartphone worth ₹25,000

Phone price: ₹25,000
GST: 12% = ₹3,000
Total price: ₹28,000

Scenario 3: Freelance Services

Situation: Providing IT services worth ₹50,000

Service fee: ₹50,000
GST: 18% = ₹9,000
Invoice amount: ₹59,000

Scenario 4: Car Purchase

Situation: Buying a car worth ₹10,00,000

Car price: ₹10,00,000
GST: 28% = ₹2,80,000
Total cost: ₹12,80,000

Frequently Asked Questions

What is the difference between GST exclusive and GST inclusive price?

GST exclusive price is the base price without tax. GST inclusive price is the final price including tax. For example, if a product costs ₹1,000 (exclusive) with 18% GST, the inclusive price is ₹1,180. Always clarify with sellers whether quoted prices include GST.

How do I know which GST rate applies to my product?

Check the HSN (Harmonized System of Nomenclature) code for goods or SAC (Service Accounting Code) for services on the GST portal. Each code has a specific GST rate. You can also consult the GST rate schedules published by the government or ask a tax professional.

Can I claim GST refund?

Yes, GST refunds can be claimed in cases like: exports (zero-rated supplies), accumulated input tax credit, excess tax payment, or tax paid by mistake. File refund application on GST portal with required documents. Refunds are typically processed within 60 days.

What happens if I don't charge GST when required?

Not charging GST when registered and required to do so can result in penalties, interest on unpaid tax, and legal action. You'll still owe the GST to the government even if you didn't collect it from customers. Always charge and collect GST as per regulations.

Is GST charged on discounts?

GST is calculated on the discounted price, not the original price. If you offer a 10% discount on ₹1,000 item, GST is calculated on ₹900. However, the discount must be given before sale and mentioned on invoice. Post-sale discounts have different rules.

Do I need to pay GST on second-hand goods?

For registered dealers, GST is payable on the margin (selling price - purchase price) for second-hand goods under the margin scheme. For unregistered individuals selling personal items, no GST applies. Different rules apply for specific categories like vehicles.

What is the penalty for late GST filing?

Late filing attracts ₹50 per day (₹20 CGST + ₹20 SGST + ₹10 fee) up to a maximum of ₹5,000. For nil returns, penalty is ₹20 per day up to ₹500. Additionally, interest at 18% per annum is charged on unpaid tax from the due date.

Can I change my GST registration details?

Yes, you can amend GST registration details like business name, address, authorized signatories, or bank account through the GST portal. Some changes require approval from GST officer, while others are auto-approved. Keep your GST details updated to avoid compliance issues.

GST Compliance Checklist

Monthly Compliance

GSTR-1: File outward supply details by 11th of next month
GSTR-3B: File summary return and pay tax by 20th of next month
Maintain Records: Keep all invoices, bills, and documents organized
Reconcile ITC: Match purchase invoices with GSTR-2A/2B

Annual Compliance

GSTR-9: Annual return (due by December 31st of next year)
GSTR-9C: Reconciliation statement (if turnover > ₹5 crores)
Audit: GST audit if turnover exceeds ₹5 crores

Tips for GST Management

Use Accounting Software: Automate GST calculations and filing
Maintain Digital Records: Keep all invoices and documents digitally
File Returns on Time: Avoid penalties and interest
Claim ITC Promptly: Don't let input credit lapse
Reconcile Regularly: Match your records with GSTR-2A monthly
Stay Updated: Follow GST notifications and rate changes
Consult Professionals: Hire CA for complex scenarios
Separate Bank Account: Maintain dedicated account for GST transactions
Issue Proper Invoices: Ensure all mandatory fields are included
Keep Backup: Maintain copies of all filed returns

Common GST Mistakes to Avoid

Wrong GST Rate: Using incorrect rate for products/services
Missing Invoices: Not maintaining proper invoice records
Late Filing: Missing return filing deadlines
Incorrect GSTIN: Using wrong GST number on invoices
Not Claiming ITC: Forgetting to claim eligible input credit
Mixing Rates: Applying wrong rate for composite supplies
Ignoring Amendments: Not updating for GST law changes
Poor Record Keeping: Inadequate documentation

GST vs Old Tax System

Aspect	Old System (Pre-GST)	GST System
Number of Taxes	Multiple (VAT, Service Tax, Excise, etc.)	Single unified tax
Tax on Tax	Yes (Cascading effect)	No (Input credit available)
Compliance	Multiple returns to different authorities	Single portal, unified returns
Inter-State Trade	Complex with CST	Simplified with IGST
Tax Rates	Varied across states	Uniform across India

Technical Performance & Accessibility

Our GST Calculator is built with modern web technologies:

Instant Calculations: Real-time results as you type
Mobile-Optimized: Touch-friendly buttons and responsive design
Print-Ready: Generate professional invoices
Accessible: WCAG AA compliant with proper labels
Privacy-First: All calculations happen locally in your browser
Fast Loading: Lightweight code ensures quick page loads
Cross-Browser: Works on all modern browsers