GST Calculator Examples for Small Businesses | Real Scenarios

What is GST?

GST (Goods and Services Tax) is a value-added tax levied on most goods and services sold for domestic consumption in India. It has replaced many indirect taxes like VAT, service tax, and excise duty.

GST rates in India

5% GST

Essential items: edible oils, sugar, tea, coffee, spices, life-saving drugs, railway travel

12% GST

Processed food, butter, ghee, almonds, mobile phones, frozen meat

18% GST

Most goods and services: soaps, hair oil, toothpaste, capital goods, restaurants (non-AC)

28% GST

Luxury goods: luxury cars, tobacco products, aerated drinks, high-end motorcycles

Example 1: Retail store selling clothes (5% GST)

Scenario: A clothing store sells a cotton shirt for ₹1,000 (excluding GST). GST rate is 5%.

Calculation:

Base price: ₹1,000
GST amount: ₹1,000 × 5% = ₹50
Final price (customer pays): ₹1,050

On invoice:
CGST: ₹25
SGST: ₹25
Total GST: ₹50

Example 2: Restaurant bill (5% or 18% GST)

Scenario: A family dines at a non-AC restaurant. Bill amount (excluding GST) is ₹1,500. GST rate is 5%.

Calculation:

Base price: ₹1,500
GST amount: ₹1,500 × 5% = ₹75
Final bill: ₹1,575

Note: AC restaurants charge 18% GST. Takeaway orders below ₹100 may have no GST (state-dependent).

Example 3: Mobile phone purchase (12% GST)

Scenario: A customer buys a mobile phone priced at ₹15,000 (excluding GST). GST rate is 12%.

Calculation:

Base price: ₹15,000
GST amount: ₹15,000 × 12% = ₹1,800
Final price: ₹16,800

Example 4: Professional services (18% GST)

Scenario: A freelance web designer charges ₹50,000 for a website project (excluding GST). GST rate is 18%.

Calculation:

Base price: ₹50,000
GST amount: ₹50,000 × 18% = ₹9,000
Final invoice: ₹59,000

Note: The freelancer must be GST-registered if annual turnover exceeds ₹20 lakhs.

Example 5: Reverse calculation (price inclusive of GST)

Scenario: A product is priced at ₹1,180 including 18% GST. What is the base price?

Calculation:

Total inclusive price: ₹1,180
Base price: ₹1,180 × 100 ÷ 118 = ₹1,000
GST amount: ₹1,180 - ₹1,000 = ₹180

Answer: Base price is ₹1,000, GST is ₹180.

Example 6: Bulk purchase for business (Input Tax Credit)

Scenario: A furniture manufacturer buys raw materials worth ₹5,00,000 (excluding GST). GST rate is 18% on raw materials.

Calculation:

Base price: ₹5,00,000
GST paid (Input): ₹5,00,000 × 18% = ₹90,000
Manufacturer sells finished furniture for ₹8,00,000 (excluding GST). GST rate on furniture is 18%.
GST collected (Output): ₹8,00,000 × 18% = ₹1,44,000
Net GST to pay: ₹1,44,000 - ₹90,000 = ₹54,000

Note: This is how Input Tax Credit (ITC) works — businesses only pay GST on the value they add.

Example 7: Inter-state sale (IGST)

Scenario: A seller in Tamil Nadu sells goods worth ₹1,00,000 to a buyer in Karnataka. GST rate is 18%.

Calculation:

Base price: ₹1,00,000
IGST amount: ₹1,00,000 × 18% = ₹18,000
Final price: ₹1,18,000

Note: For inter-state sales, IGST (Integrated GST) is charged instead of CGST + SGST.

Example 8: Ecommerce seller (TCS)

Scenario: An ecommerce platform like Amazon sells a product for ₹10,000. GST rate is 18%. The platform collects Tax Collected at Source (TCS) at 1%.

Calculation:

Product price: ₹10,000
GST (18%): ₹1,800
TCS (1% on ₹10,000): ₹100
Customer pays: ₹10,000 + ₹1,800 + ₹100 = ₹11,900

GST calculation formulas

Add GST (Exclusive → Inclusive)

GST Amount = (Original Price × GST%) ÷ 100

Total Price = Original Price + GST Amount

Remove GST (Inclusive → Exclusive)

Original Price = (Total Price × 100) ÷ (100 + GST%)

GST Amount = Total Price - Original Price

Common GST mistakes to avoid

❌ Using the wrong GST rate — Verify HSN/SAC codes before billing
❌ Not registering for GST — Required if turnover exceeds ₹40 lakhs (goods) or ₹20 lakhs (services)
❌ Missing invoice details — Include GSTIN, HSN code, tax amount, and place of supply
❌ Not filing GSTR-3B monthly/quarterly — Late fees apply
❌ Confusing CGST/SGST with IGST — Intra-state = CGST+SGST, Inter-state = IGST
❌ Not claiming Input Tax Credit — You can claim GST paid on business purchases

GST registration limits (India)

Goods (normal states): ₹40 lakhs annual turnover
Goods (special category states): ₹20 lakhs
Services (all states): ₹20 lakhs (₹10 lakhs for special category)
Ecommerce sellers: Mandatory registration regardless of turnover
Casual taxable persons: Mandatory registration

Frequently asked questions

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

For intra-state sales: CGST (Central) + SGST (State) = Total GST. For inter-state sales: IGST (Integrated GST) = Total GST.

Do I need to charge GST on my products?

If your annual turnover exceeds ₹40 lakhs (₹20 lakhs for special category states) for goods, or ₹20 lakhs for services, you need GST registration.

What is the GST on restaurant bills?

5% GST for non-AC restaurants, 18% for AC restaurants. No GST on takeaways below ₹100 (some states).

How do I calculate reverse GST?

Use our GST Calculator with "Remove GST" option. Enter the inclusive amount to get the exclusive price.