GST Calculator — Add or Remove GST Online Free
Calculate GST on any amount instantly. Add GST to get the tax-inclusive total, or use reverse GST to find the base price from a GST-inclusive amount. Shows CGST, SGST & IGST split.
Calculate GST on Amount
Intrastate = seller & buyer in same state. Interstate = different states.
GST Breakdown
Pre-GST Amount (input)
₹10,000.00
GST Amount (18%)
₹1,800.00
Total GST-Inclusive Amount (result)
₹11,800.00
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How to Calculate GST Online Using This Tool
- 1Select the mode: "Add GST" to find the GST-inclusive total from a base price, or "Remove GST" to extract the base price from a GST-inclusive amount.
- 2Enter the amount in the input field.
- 3Select the applicable GST rate — 5%, 12%, 18%, or 28%.
- 4Choose the transaction type: Intrastate (same state, shows CGST + SGST split) or Interstate (different states, shows IGST).
- 5View instant results — base amount, GST breakdown (CGST/SGST or IGST), and total amount.
GST Calculation Formula & Method
Two modes of GST calculation are used in practice:
Add GST (Exclusive → Inclusive)
GST = Amount × Rate ÷ 100
Total = Amount + GST
Example: ₹10,000 at 18%
GST = ₹10,000 × 18 ÷ 100 = ₹1,800
Total = ₹10,000 + ₹1,800 = ₹11,800
Remove GST (Inclusive → Exclusive)
Base = Total ÷ (1 + Rate ÷ 100)
GST = Total − Base
Example: ₹11,800 at 18%
Base = ₹11,800 ÷ 1.18 = ₹10,000
GST = ₹11,800 − ₹10,000 = ₹1,800
CGST + SGST vs IGST Split
Intrastate (same state):
CGST = Total GST ÷ 2
SGST = Total GST ÷ 2
At 18%: CGST = 9%, SGST = 9%
Interstate (different states):
IGST = Total GST (full rate)
At 18%: IGST = 18%
GST Calculation Example with Indian Numbers
Scenario: IT freelancer invoicing a Mumbai client ₹50,000 for web development (18% GST, intrastate)
| Service Value (pre-GST) | ₹50,000 |
| GST Rate | 18% |
| Total GST | ₹9,000 |
| CGST @ 9% | ₹4,500 |
| SGST @ 9% | ₹4,500 |
| Invoice Total | ₹59,000 |
The client pays ₹59,000. The freelancer collects ₹9,000 GST and remits it to the government (minus any ITC credits). Net revenue = ₹50,000.
Common GST Calculation Mistakes to Avoid
Confusing GST-inclusive and GST-exclusive prices
When a vendor quotes "₹11,800 inclusive of 18% GST", the actual value is ₹10,000 — not ₹11,800 − 18% of ₹11,800 (which would be wrong). Always use the reverse GST formula: Base = Total ÷ (1 + rate/100).
Applying IGST for same-state transactions
If you and your client are in the same state, GST splits into CGST + SGST (half each). Applying IGST for intrastate transactions is an error that creates reconciliation issues in GSTR returns.
Using wrong GST rate for services
Most professional services (freelance work, IT, consulting) attract 18% GST. Some assume 12% applies to all business-to-business services — this is incorrect. Always verify the HSN/SAC code and applicable rate for your specific service.
Not registering for GST after crossing ₹20 lakh turnover
Once your aggregate annual turnover exceeds ₹20 lakh (₹10 lakh in special category states), GST registration is mandatory. Continuing to issue invoices without GST registration after crossing this threshold attracts penalties.
Frequently Asked Questions — GST Calculator
Q: What is GST and how is it calculated in India?
GST (Goods and Services Tax) is a unified indirect tax levied on the supply of goods and services in India. It replaced multiple taxes like VAT, service tax, and excise duty. GST is calculated as a percentage of the transaction value. For example, on ₹10,000 at 18% GST: GST amount = ₹10,000 × 18% = ₹1,800; Total = ₹11,800.
Q: How to calculate 18% GST on an amount?
To add 18% GST: multiply the amount by 0.18 to get the GST portion, then add it to the original amount. Example: ₹50,000 × 18% = ₹9,000 GST. Total = ₹59,000. To remove 18% GST from an inclusive price: Base = Total ÷ 1.18. Example: ₹59,000 ÷ 1.18 = ₹50,000.
Q: What is reverse GST calculation?
Reverse GST (or "Remove GST") finds the pre-tax base price when you know the GST-inclusive total. Formula: Base Price = GST-Inclusive Total ÷ (1 + GST Rate/100). For ₹11,800 at 18%: Base = ₹11,800 ÷ 1.18 = ₹10,000. GST amount = ₹11,800 − ₹10,000 = ₹1,800. This is used when a vendor quotes a GST-inclusive price and you need to know the net value.
Q: What is the difference between CGST, SGST, and IGST?
CGST (Central GST) and SGST (State GST) together apply to intrastate transactions (seller and buyer in the same state). Each is half the total GST rate — so on 18% GST, CGST = 9% and SGST = 9%. IGST (Integrated GST) applies to interstate transactions (seller and buyer in different states) and equals the full GST rate (18% in this case). The revenue from CGST goes to the central government, SGST to the state government, and IGST is shared between both.
Q: When does IGST apply vs CGST + SGST?
CGST + SGST applies when the place of supply is in the same state as the supplier (intrastate). IGST applies when the place of supply is in a different state than the supplier (interstate), or for imports/exports. For example, a Mumbai supplier selling to a Delhi buyer uses IGST. A Mumbai supplier selling to another Mumbai business uses CGST + SGST.
Q: What are the 4 GST rates in India?
India has four main GST rates: 5% (essential goods and services — basic foods, transport), 12% (processed foods, business-class travel, work contracts), 18% (most services including professional fees, IT services, restaurants, electronics), and 28% (luxury goods, automobiles, tobacco, aerated drinks). A 0% rate applies to exempt goods like fresh vegetables and educational services.
Q: How to add GST to an invoice amount?
On a GST invoice: 1) List each item with its pre-GST value. 2) Apply the applicable GST rate to each item. 3) For intrastate: split GST into equal CGST and SGST. For interstate: show as IGST. 4) Sum the pre-GST values for the subtotal. 5) Sum all GST amounts. 6) Grand Total = Subtotal + Total GST. This calculator handles the math automatically — enter your pre-GST amount and select "Add GST".
Q: Is GST charged on services in India?
Yes. GST applies to services in India. Most services fall under the 18% slab — including professional fees (consultancy, legal, CA), IT services, telecom, advertising, banking, and restaurant services. Some services are exempt: healthcare, education, and basic financial services. Freelancers and service providers with annual turnover above ₹20 lakh (₹10 lakh in some states) must register for GST.
Q: What is the GST exemption limit for freelancers?
Freelancers and service providers must register for GST if their annual turnover exceeds ₹20 lakh (₹10 lakh for special category states in Northeast India). Below this threshold, GST registration is optional (but voluntary registration is allowed). Once registered, you must charge GST on all invoices, file monthly/quarterly returns, and can claim Input Tax Credit on business purchases.
Q: Can I claim GST paid on purchases (Input Tax Credit)?
Yes — registered GST taxpayers can claim Input Tax Credit (ITC) on GST paid for business-related purchases and expenses. ITC reduces your net GST payable. Example: if you collected ₹18,000 GST from clients but paid ₹6,000 GST on purchases, you only remit ₹12,000 to the government. ITC cannot be claimed on personal expenses, food, and certain blocked credits under Section 17(5) of the GST Act.
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