About this tool
Two calculations live here, and only one of them is obvious. Adding GST to a price is a multiplication anyone can do in their head. Taking GST out of a price that already contains it is a division, and that is where invoices go wrong.
The wrong method is to subtract the rate. Eighteen per cent of ₹1,180 is ₹212.40, so the taxable value must be ₹967.60. Except it is not. The right answer is ₹1,000, because the ₹180 of tax was calculated on the thousand, not on the eleven-eighty. You divide by 1.18. The error is small on one line and compounds quickly across a month of them, and it is the reason the “price including GST” setting is here rather than left to mental arithmetic.
The second thing the tool does is show you both splits at once. Whether a transaction is CGST plus SGST or a single IGST turns on the place of supply, which the tool has no way of knowing. Rather than pick for you, it prints both: half and half for a sale within one state, the full figure as IGST for a sale that crosses a state line or leaves the country. The total tax is identical either way: only the columns on the invoice change.
Everything runs in your browser. No figure from your books is sent anywhere, which matters more for a page you might use on a phone in someone else’s shop than it does at your own desk.
How to use this tool
- Enter the amount. Either the price before tax or the price with tax already in it. The next setting tells the tool which one you typed.
- Say which one it is. “Price before GST” adds the tax on top. “Price including GST” works backwards to find the taxable value hidden inside it.
- Pick the rate. The rates in force since 22 September 2025 are listed: 5% and 18% as the two main slabs, 40% for luxury and sin goods, 3% for gold, silver and jewellery, and 0.25% for rough diamonds. The old 12% and 28% slabs no longer exist.
- Take the line your invoice needs. A sale inside one state splits into CGST and SGST at half each. A sale across state lines is a single IGST figure. Both are shown; use the one that applies.
What this tool does not do
- Duties outside GST, such as those on tobacco and pan masala, are not calculated.
- It does not tell you which slab your product or service falls into.
- Reverse charge, composition scheme and TCS are outside what it does.
- It applies one rate to one amount. It will not total a multi-line invoice.
- It is not a tax invoice and does not check anything against GSTN.
Common questions
How do you remove GST from a price that includes it?
You divide, you do not subtract. To strip 18% from ₹1,180, divide by 1.18 to get ₹1,000, not subtract 18% of ₹1,180, which would leave ₹967.60 and be wrong by over thirty rupees. This is the single most common GST mistake, and it is why the “price including GST” setting exists.
When is it CGST and SGST, and when is it IGST?
It depends on the place of supply, not on where your bank is. Supplier and place of supply in the same state means CGST plus SGST, half the rate each. Different states, or a supply to a union territory or an export, means IGST at the full rate. The total tax is the same either way; only the split changes.
Why does the tool show both splits?
Because it cannot know where your buyer is, and guessing would be worse than showing you both. Read the line that matches the invoice you are writing.
What about the GST cess?
Not included. Compensation cess is no longer charged on any goods or services from 1 February 2026. Tobacco and pan masala now carry separate duties outside GST, which this tool does not calculate.
Is the rate list current?
The list matches the rates in force from 22 September 2025, when the GST Council replaced the 12% and 28% slabs with 5%, 18% and 40%. Which slab a specific good or service falls into is a separate question, changes at council meetings, and is not something this tool decides. Check the HSN or SAC code for your item.
Can I use this output on an invoice?
The arithmetic, yes. A tax invoice also needs your GSTIN, the buyer's GSTIN, HSN or SAC codes, the place of supply and an invoice number in a continuous series. This gives you the figures, not the document.