Calculators
GST Calculator
Both directions of GST in one tool: add tax to a base price or pull the tax out of an inclusive price, with the CGST/SGST halves ready for your invoice.
In short
GST is India's Goods and Services Tax. Since 22 September 2025 most goods and services attract either the 5% merit rate or the 18% standard rate, with a special 40% de-merit rate for a select few goods and services. This calculator adds GST to a net price or extracts it from an inclusive one, and shows the CGST/SGST split.
By NaveenKumar T · Updated
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- Add GST or remove (reverse) GST
- 0/5/18/40% presets + custom rate
- CGST / SGST split
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India's GST slabs changed in September 2025
At its 56th meeting on 3 September 2025 the GST Council replaced the four-tier 5/12/18/28 structure with a two-rate structure — a 5% merit rate and an 18% standard rate — plus a special 40% de-merit rate for a select few goods and services, with NIL for exempt items (PIB press release, 3 September 2025). The new rates took effect on 22 September 2025 for services and for all goods except pan masala, gutkha, cigarettes, chewing tobacco, unmanufactured tobacco and bidi, which continue at their existing rates plus compensation cess until the cess-account loans are repaid. The 40% rate covers items such as aerated and sugary drinks and caffeinated beverages; many goods formerly at 12% moved to 5%, and many formerly at 28% moved to 18%, listed item by item in the release's annexures.
The presets below reflect the current slabs — use the custom-rate field for the old 12%/28% rates if you're re-checking a pre-reform invoice, or for VAT elsewhere.
Reverse GST: the calculation everyone gets wrong
Extracting tax from an inclusive price is the most common GST task — and the most commonly botched, because intuition says 'multiply by the rate'. The correct move divides first: net = gross ÷ (1 + rate/100), then tax = gross − net. This calculator does it right in 'remove' mode, to the exact decimal, for any rate including the current 0/5/18/40 slabs.
For invoicing inside a state, the CGST and SGST cards give you the two half-rate line items auditors expect; quote the full amount as IGST for inter-state supplies. The same add/remove math applies to any VAT-style tax — set a custom rate and the tool works for GST in Australia or Singapore, or VAT anywhere.
Remove GST from a total (reverse GST)
Side by side, the two directions on the same ₹1,000 show why they need different formulas: adding GST multiplies (tax = net × rate ÷ 100), while removing it from an already-inclusive total divides first (net = gross ÷ (1 + rate/100), then tax = gross − net). The table below is exact to the paisa for the four current slabs.
| GST rate | ₹1,000 exclusive (add GST) | ₹1,000 inclusive (remove GST) |
|---|---|---|
| 0% | ₹1,000.00 + ₹0.00 tax = ₹1,000.00 | ₹1,000.00 = ₹1,000.00 net + ₹0.00 tax |
| 5% | ₹1,000.00 + ₹50.00 tax = ₹1,050.00 | ₹1,000.00 = ₹952.38 net + ₹47.62 tax |
| 18% | ₹1,000.00 + ₹180.00 tax = ₹1,180.00 | ₹1,000.00 = ₹847.46 net + ₹152.54 tax |
| 40% | ₹1,000.00 + ₹400.00 tax = ₹1,400.00 | ₹1,000.00 = ₹714.29 net + ₹285.71 tax |
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Frequently asked questions
Everything you need to know about the GST Calculator.
01Is GST charged on the discounted price or the list price?
On the discounted price, when the discount is shown on the invoice at the time of supply — that is the value of supply the GST law recognises. A discount agreed later is excluded only if it was agreed before the sale and the buyer reverses the matching input tax credit. So compute the discount first, then add GST to the reduced amount: 2,000 less 20% is 1,600, and 18% GST on that is 288, not 360.
02How do you add and remove GST correctly?
Adding is simple: tax = net × rate ÷ 100. Removing is where people slip: the tax inside a gross amount is gross − gross ÷ (1 + rate/100) — not gross × rate ÷ 100. At 18%, an inclusive 1,180 contains exactly 180 of tax; multiplying 1,180 by 18% would wrongly give 212.40.
03When is it CGST + SGST and when is it IGST?
Within one Indian state, GST splits equally into central and state halves (CGST + SGST — this tool shows both). Across state lines it's a single IGST at the full rate. The total tax is identical either way; only the invoice line items differ.
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