GST Calculator (India)
This GST calculator adds or removes India's Goods and Services Tax from any amount at the four standard slabs — 5%, 12%, 18% and 28%. Choose whether your entered amount excludes GST (and you want to add it) or already includes GST (and you want to break it down), then pick the applicable rate to see the exact tax and base figures.
The amount you want to add GST to, or the GST-inclusive amount you want to break down — depends on the calculation type below.
The standard GST slab that applies to your goods or service.
Add GST if your amount excludes tax. Remove GST if your amount already includes tax and you want to break it down.
GST amount
Log in to save₹1,800
For a sale between two different states, IGST applies instead — the full GST amount as a single tax, with no CGST/SGST split.
How to use this gst calculator
- 1Amount: enter the amount before GST (if adding) or the GST-inclusive amount (if removing).
- 2GST rate: pick the slab that applies to your goods or service — 5%, 12%, 18% or 28%.
- 3Calculation type: 'Add GST' treats your amount as excluding tax; 'Remove GST' treats it as already including tax and works backward to the base amount.
Understanding your results
GST amount is the tax itself. Base amount is the value before GST is applied. Total amount is what's actually paid or invoiced — base plus GST. CGST + SGST (each) shows how the GST amount splits for a transaction within the same state — for an inter-state transaction, IGST applies instead, charged as the full GST amount with no split.
The formula
Add GST: Total = Amount × (1 + Rate/100) | Remove GST: Base = Total × 100/(100 + Rate)Adding GST is straightforward multiplication: the GST amount is the entered amount times the rate, and the total is the amount plus that tax. Removing GST works backward — since the entered amount already includes tax, dividing by (100 + rate) and multiplying by 100 recovers the pre-tax base amount; the GST amount is then the difference between the inclusive amount and that base.
A worked example
Adding 18% GST to a ₹10,000 amount gives a GST amount of ₹1,800 and a total of ₹11,800 — split as ₹900 CGST + ₹900 SGST for an intra-state sale. Running the reverse calculation on that same ₹11,800 inclusive amount at 18% recovers the same ₹10,000 base and ₹1,800 GST amount, confirming the two calculation types are exact inverses of each other.
Things to know
India's GST has four standard slabs: 5% typically applies to essential goods and services, 12% and 18% cover most standard goods and services (18% is the most common slab), and 28% applies to luxury and sin goods. GST is a destination-based consumption tax, collected at each stage of the supply chain but ultimately borne by the end consumer. For a sale within the same state, the tax splits into CGST (Central GST) and SGST (State GST), each exactly half of the total GST amount; for a sale between two different states, IGST (Integrated GST) applies instead, as a single tax equal to the full GST amount. Always verify which slab applies to your specific goods or service against current CBDT/official GST Council guidance, since exact classifications and rates can change.
Frequently asked questions
How do I know if I should add or remove GST?+
If you have a base price and need to work out what to charge including tax, use 'Add GST'. If you have an invoice or receipt total that already includes GST and want to know the tax and base amount within it, use 'Remove GST'.
Why does removing GST not simply divide by the rate?+
Because the rate applies to the base amount, not the inclusive total — dividing the inclusive amount by (100 + rate) and multiplying by 100 correctly recovers the base amount that, when GST is added back, reproduces the original inclusive figure.
What's the difference between CGST/SGST and IGST?+
CGST and SGST apply together on transactions within the same state, splitting the GST amount equally between the central and state governments. IGST applies instead on transactions between two different states, charged as a single tax equal to the full GST amount and later apportioned between the states involved. Always confirm the correct treatment for your specific transaction against current CBDT/official guidance.
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