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GST calculator: add GST, take it out, split CGST and SGST
To add GST, multiply the price by the rate: ₹1,000 at 18% is ₹180 of GST, ₹1,180 in all. To take GST out of a price that already includes it, multiply by rate ÷ (100 + rate): ₹1,180 × 18 ÷ 118 = ₹180, which leaves ₹1,000.
Within one state the tax is split half CGST and half SGST; between states it is all IGST. The calculator rounds to the paisa and shows the step — it does not tell you which rate applies to your goods or service.
Everything is worked out in your browser. Nothing you type is saved or sent anywhere — no sign-up, no account, and the numbers never leave this device.
Adding GST to a price
GST = price × rate ÷ 100, and the total is the price plus the GST. An invoice of ₹2,400 before GST at 5% carries ₹120.00 of GST — ₹60.00 CGST and ₹60.00 SGST if the sale is inside one state — and comes to ₹2,520.00. At 18%, ₹2,500 carries ₹450.00 and comes to ₹2,950.00.
Taking GST out of an MRP or a price that includes it
When a price already has the GST inside it — an MRP, or a menu price quoted with taxes — the tax inside is price × rate ÷ (100 + rate), and the price before tax is what is left. A bottle with an MRP of ₹40 at 5% holds 40 × 5 ÷ 105 = ₹1.90 of GST, so ₹38.10 before tax.
Two mistakes are common. One is to take the rate straight off the MRP: 5% of ₹40 is ₹2.00, which is not the tax inside it. The other is to work out the price before tax, round it, and add the tax back: ₹38.10 plus 5% is ₹40.01 — a paisa over the MRP. Taking the tax out, never building it back up, keeps the MRP exact. It is how Nivasik’s counter handles MRP prices.
| Rate | Working | GST inside ₹100 | Price before GST |
|---|---|---|---|
| 5% | 100 × 5 ÷ 105 | ₹4.76 | ₹95.24 |
| 12% | 100 × 12 ÷ 112 | ₹10.71 | ₹89.29 |
| 18% | 100 × 18 ÷ 118 | ₹15.25 | ₹84.75 |
| 28% | 100 × 28 ÷ 128 | ₹21.88 | ₹78.12 |
| 40% | 100 × 40 ÷ 140 | ₹28.57 | ₹71.43 |
CGST, SGST and IGST
Inside one state or union territory, GST is charged as two equal halves: CGST for the Centre and SGST — UTGST in a union territory — for the state. At 18% that is 9% + 9%. When goods or services go from one state to another, the whole rate is charged as IGST. Which one applies depends on the place of supply, which the GST law defines; the calculator lets you choose and does not work it out for you.
When the tax comes to an odd number of paise it cannot be split evenly. The calculator rounds CGST to the paisa and gives SGST the rest, so the two always add up to the tax on the invoice.
Which GST rate applies?
This calculator computes; it does not advise. The rate for goods depends on their HSN code, and for a service on its SAC code, as notified by the Government. Rates were restructured from 22 September 2025: on the GST Council’s recommendation most goods and services moved to two main rates, 5% and 18%, with a special rate of 40% for a few, while certain tobacco products stayed on their earlier rates for a time. 12% and 28% stay in the list for older bills and for anything still charged at them.
To check the rate for your item, search its HSN or SAC code on the GST portal, and confirm it with your accountant. The sources below are the official ones. For hotel rooms and restaurant bills, the guide to GST on hotels and restaurants sets out the rates in force with the notification behind each one.
GST on every bill, without a calculator
In Nivasik the tax is worked out on the bill itself, from the rate you set on each item or charge:
- MRP prices taken apart correctly — the tax comes out of the price, never on top of it.
- GST invoices whose preview matches the invoice that is issued, with CGST and SGST or IGST.
- Reports down to GST by HSN, with GSTR-1 data and a Tally import file (CSV) for your accountant.
What it does not do
- It prepares the GST data; it does not file your return.
- There is no e-invoice (IRN) or e-way bill.
- Tally gets an import file, not a live connection.
Questions people ask
How do I calculate GST on an amount?
Multiply the amount by the rate and divide by 100. At 18%, the GST on ₹2,500 is ₹450, making ₹2,950. Within one state that is ₹225 CGST and ₹225 SGST.
How do I remove GST from a total?
Multiply the total by rate ÷ (100 + rate) to find the GST inside it, then subtract. For ₹2,950 at 18%: 2,950 × 18 ÷ 118 = ₹450, which leaves ₹2,500 before GST.
What is the difference between CGST, SGST and IGST?
CGST and SGST (or UTGST) are the two halves of GST on a sale within one state or union territory. IGST is the whole rate on a sale from one state to another. The total rate is the same; what differs is who collects it.
Which GST rate applies to my product or service?
It depends on the HSN code of the goods or the SAC code of the service, as notified by the Government. Search the code on the GST portal and confirm with your accountant — this calculator does not decide it.
Why is CGST sometimes a paisa more than SGST?
When the tax comes to an odd number of paise it cannot be split into two equal halves. The calculator rounds CGST to the paisa and gives SGST the rest, so the two always add up to the tax.
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Last reviewed 25 September 2026. The calculator does arithmetic; it is not tax advice.
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