C.K. Gupta
In short
We compared five genuinely free GST calculators in October 2026 — no signups, no paywalls. The key test after the September 2025 GST 2.0 reform (12% and 28% slabs withdrawn; 5%, 18%, 40% plus 3% and 0.25% special rates) is whether a calculator still carries the old slabs: two of the five do, including in their own rate tables. TaxGST.in’s calculator covers the complete GST 2.0 rate set; ToolAdda is the strongest on privacy and invoice extras; GSTCalc.in helps most with picking the right slab. No calculator can tell you which rate your product attracts — that is a classification question, not a maths question.
Verified October 2026 · TaxGST.in
How we compared them
A GST calculator does one job: apply a rate you supply to an amount, forward (add GST) or backwards (remove GST), and split it into CGST/SGST or IGST. We tested each tool against five practical criteria:
- GST 2.0 rate coverage — does it reflect the post-September 2025 slabs (5%, 18%, 40%, plus 3% gold and 0.25% rough diamonds) rather than the withdrawn 12% and 28%?
- Add and remove modes — can it both add tax to a base price and extract tax from a GST-inclusive price?
- CGST/SGST/IGST split — does it show the intra-state vs inter-state breakup correctly?
- Extras — custom rates, invoice copy, round-off handling, rate references.
- Privacy and cost — free without signup, and does your data leave your browser?
1. TaxGST.in GST Calculator — best for complete GST 2.0 rates
Our own calculator supports the full notified rate set: 0%, 0.25%, 1.5%, 3%, 5%, 18% and 40% — including the niche 0.25% rough-diamond rate that most tools skip. It handles both add-GST and remove-GST modes, shows the CGST/SGST vs IGST split, and lets you export results. Free, no signup.
Pros: the only tool in this list with the complete GST 2.0 slab coverage; verified against the notified schedule in October 2026; exportable results; part of a 44-tool free calculator suite, so the income tax calculator and others are one click away.
Cons: a focused single-purpose tool — there is no inline product-rate reference on the calculator page itself, so you need to know your slab (or check it in the GST Hub) before you calculate.
2. ToolAdda GST Calculator — best for privacy and invoice detail
ToolAdda runs entirely in your browser — the page states nothing is uploaded, which matters if you are calculating client figures on a shared machine. It also has the best invoice-oriented extras: an optional round-off line (Indian invoices commonly round to the nearest rupee and show the adjustment separately), a local calculation history (last 12, stored only in your browser, off by default), and a custom-rate option from 0% to 100%. It even handles the fiddly paisa rounding correctly — ₹15.25 of GST splits as ₹7.63 CGST + ₹7.62 SGST so the invoice reconciles to the paisa.
Pros: genuinely private (no server round-trip); thoughtful extras for invoicing; extensive worked examples and guides on the same page; free, mobile-friendly, no signup.
Cons: its rate-reference table still lists the withdrawn 12% and 28% slabs alongside current rates — check the slab yourself against the September 2025 rationalisation before relying on a preset.
3. GSTCalc.in — best for choosing the right slab
Where most calculators make you supply the rate and hope for the best, GSTCalc.in attacks the real problem: which slab does your product fall in? It ships a rate list covering 125 everyday products and services, is updated for FY 2026-27, and explicitly warns that AI chatbots still quote pre-reform GST rates after the September 2025 restructuring — a warning we agree with.
Pros: strongest slab-picking help of the five; current for FY 2026-27; clean instant calculation.
Cons: a product-rate list is a guide, not a legal determination — for genuinely arguable classifications, confirm against the notified HSN/SAC schedule rather than any tool’s table.
4. StartBusiness GST Calculator — best for copy-paste invoicing
StartBusiness’s tool is built around speed: results update as you type (no calculate button), there are amount presets like ₹10,000, and a “copy for invoice” button that puts the full breakdown on your clipboard for pasting into billing software. Its rate guide correctly reflects the September 2025 reform, and the page notes it was reviewed by a practising CA with rates verified against the notified schedule.
Pros: fastest workflow of the five for repetitive invoicing; good explanatory content (supply chain, registration thresholds); reviewed by a CA.
Cons: the page’s own FAQ block still answers “What are the GST slabs in India 2026?” with the old 0/5/12/18/28% list — directly contradicting the updated guide higher up the same page. Follow the updated table, not the stale FAQ.
5. VyaparGateway GST Calculator — best no-nonsense merchant option
VyaparGateway positions itself as the anti-annoyance option: no ads, no signup, calculations run locally in your browser. Beyond the basics it adds a profit-margin view (enter cost price and see net margin alongside tax — genuinely useful for quotes) and one-tap WhatsApp share of the result. It supports both add and remove modes with auto CGST/SGST/IGST splitting.
Pros: no ads or signup; margin calculator built in; local computation; WhatsApp share for quick quotes.
Cons: its “current” 2026 rate table still lists 12% and 28% as active slabs (computers at 12%, automobiles at 28%) — both withdrawn in the 2025 reform. Verify any preset against the notified schedule before using it on an invoice.
Side-by-side comparison
| Tool | Free, no signup | Add + remove | CGST/SGST/IGST split | GST 2.0 slabs current | Standout |
|---|---|---|---|---|---|
| TaxGST.in | Yes | Yes | Yes | Yes — 0.25%, 1.5%, 3% included | Complete notified rate set |
| ToolAdda | Yes | Yes | Yes | Partial — 12%/28% still listed | Privacy + invoice round-off |
| GSTCalc.in | Yes | Yes | Yes | Yes (FY 2026-27) | 125-product slab finder |
| StartBusiness | Yes | Yes | Yes | Yes, but stale FAQ block | Type-to-calculate + copy-for-invoice |
| VyaparGateway | Yes | Yes | Yes | No — 12%/28% shown as current | No ads + margin view |
Which one should you use?
- Everyday invoicing with unusual rates (jewellery at 3%, diamonds at 0.25%): use the TaxGST.in GST Calculator — it is the only one here with the niche GST 2.0 rates.
- Client or sensitive figures on a shared device: ToolAdda, because nothing leaves your browser.
- Not sure which slab your product attracts: start at GSTCalc.in’s 125-product list, then calculate anywhere.
- Repetitive quotes and invoices: StartBusiness for its live-as-you-type and copy-for-invoice flow, or VyaparGateway for its margin view and WhatsApp sharing.
And whichever you pick: the number-one post-reform mistake is applying a slab that no longer exists. The 12% and 28% slabs were withdrawn with effect from 22 September 2025 — if a tool’s preset or FAQ still offers them, treat that as a red flag, not a rate. For the full compliance picture — due dates, returns, registration — keep the Compliance Calendar Hub handy.
Frequently Asked Questions
Are these GST calculators really free?
Yes — all five calculate without signup or payment. The “cost” to watch for is stale rates, not pricing: a free calculator quoting a withdrawn slab is more expensive than any paid tool.
What are the current GST slabs in India (October 2026)?
5%, 18% and 40%, following the September 2025 reform (effective 22 September 2025), plus special rates of 3% for gold and jewellery and 0.25% for rough diamonds. The 12% and 28% slabs were withdrawn — most 12% items moved to 5%, most 28% items to 18%.
Can a GST calculator tell me which rate applies to my product?
No. Calculators apply the rate you give them. Rate classification depends on HSN codes (goods) and SAC codes (services) in the notified schedules — use a rate list or the CBIC notifications, then calculate.
What is the difference between adding and removing GST?
Adding GST takes a base price and adds tax on top (₹10,000 + 18% = ₹11,800) — for quotes and invoices. Removing GST extracts the tax from a price that already includes it (₹11,800 inclusive of 18% = ₹10,000 base + ₹1,800 tax) — for MRP-based accounting and ITC reconciliation. The common mistake is taking 18% of the inclusive figure directly, which overstates the tax.
Is it safe to use these calculators for client billing data?
ToolAdda and VyaparGateway both state calculations run locally in your browser with nothing stored on servers — the safest option for sensitive figures. The others are standard web tools; avoid entering anything beyond amounts and rates.
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