GST Calculator — Free Online Tool
Add or remove GST at 5%, 12%, 18% or 28% — inclusive & exclusive. · No signup · Works on mobile
100% private: your data is processed in your browser. Nothing is uploaded to our servers.
How to use the gst calculator
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Enter the amount and select whether it already includes GST or not.
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Pick the GST slab — 5%, 12%, 18%, 28% — or type a custom rate.
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Read the base amount, GST amount, CGST/SGST split, and final total instantly.
What does this tool do?
This free GST calculator adds or removes Goods and Services Tax from any amount in one click. Choose a rate (5%, 12%, 18%, 28% or custom), pick whether your price is GST-inclusive or exclusive, and instantly see the net amount, GST amount, and the CGST/SGST split.
How does the gst calculator work?
For exclusive prices, GST = amount × rate/100. For inclusive prices, the tool extracts GST using GST = amount − (amount × 100/(100+rate)). Intra-state transactions split GST equally into CGST and SGST; inter-state transactions use IGST at the full rate.
Frequently Asked Questions
How do I remove GST from an inclusive price?
Divide the inclusive price by (1 + rate/100). For a ₹1,180 price that includes 18% GST: 1180 ÷ 1.18 = ₹1,000 base, so the GST portion is ₹180. This calculator does the division for you and shows both figures instantly.
What is the difference between CGST, SGST and IGST?
For sales within one Indian state, GST is split equally: CGST goes to the central government and SGST to the state (18% GST = 9% + 9%). For inter-state sales, the full amount is charged as IGST to the centre. The total tax you pay is identical either way.
Is the GST calculator really free?
Yes — 100% free with no hidden charges, trial limits, or premium tiers for core features. You don't need to create an account or enter an email address. The site is supported by non-intrusive display ads, which keeps every tool free for everyone.
Is my data private when using the GST calculator?
Completely. The GST calculator runs entirely in your browser using JavaScript — nothing you type or upload is sent to our servers. When you close the tab, your data is gone. This makes it safe for confidential documents, financial figures, and personal information.
Does the GST calculator work on mobile phones?
Yes. The GST calculator is built mobile-first and works on any phone or tablet with a modern browser — iPhone (Safari), Android (Chrome), and everything in between. The layout adapts to small screens, so buttons and inputs stay easy to tap on a 375px-wide display.
Do I need to install anything to use the GST calculator?
No. The GST calculator works directly in your web browser — no downloads, no extensions, no signup. Just open the page, use the tool, and get your result instantly. It works on Windows, macOS, Linux, ChromeOS, iOS, and Android.