Free calculator · India
GST calculator: add or remove GST in seconds
Type a price to see the tax.
You will get the price before tax, the tax itself (split the way an invoice shows it) and the total.
How to use it
There are only three decisions, and the calculator asks for them in this order:
- Add or remove? Choose “Add GST” when your price is the amount before tax and you want to know what to charge. Choose “Remove GST” when the price already includes tax, as most shelf prices in India do.
- What rate? Tap one of the common rates or type your own. If you are not sure which rate your product carries, see the note below.
- Same state or another state? That decides whether you see CGST and SGST, or IGST.
The formulas, if you like to check
Adding GST
GST = price × rate ÷ 100
Total = price + GST
₹2,500 at 12%: GST = 2,500 × 12 ÷ 100 = ₹300. Total ₹2,800.
Removing GST
Price before GST = total × 100 ÷ (100 + rate)
GST = total − price before GST
₹2,800 with 12% included: 2,800 × 100 ÷ 112 = ₹2,500. GST is ₹300.
Splitting into CGST and SGST
Inside one state, the tax is cut in two equal halves. At 18%, a ₹10,000 sale carries ₹900 CGST and ₹900 SGST. Between two states the same ₹1,800 appears as a single IGST line. The customer pays ₹11,800 in both cases. What changes is who the money is credited to, and which columns your invoice and your return use.
Which rate should I type?
This is the part no calculator can do for you, and we would rather say so than guess. The rate belongs to the item, not to you: the same shop can sell some goods at 5% and others at 18%. Find your item’s HSN code (for goods) or SAC code (for services) and read the rate against it in the schedules published on the CBIC website. Rates also change over time, and the one that applies generally follows the time of supply, so for a sale made around a change of rate, check which one applies before you invoice.
From a number to an invoice
A calculator tells you the tax on one price. An invoice has to show it properly: your GSTIN, your customer’s details, the place of supply, the HSN or SAC code and the tax by rate. Our free GST invoice generator uses the same maths as this page, so the numbers you just checked are the numbers that end up on the PDF.
Questions people ask
How do I calculate GST on a price?
Multiply the price by the GST rate and divide by 100. For ₹10,000 at 18%, GST is 10,000 × 18 ÷ 100 = ₹1,800, so the customer pays ₹11,800. The calculator above does this, and also splits the tax into CGST and SGST (or IGST) the way an invoice shows it.
How do I take GST out of a price that already includes it?
Divide the price by 1 plus the rate. For ₹11,800 with 18% included, the price before GST is 11,800 ÷ 1.18 = ₹10,000, and the GST is the difference, ₹1,800. A common mistake is to take 18% of ₹11,800, which gives ₹2,124 and a wrong answer. Use the 'Remove GST' button.
Is GST worked out before or after a discount?
On the price after the discount, when the discount is given at the time of sale and shown on the invoice. If a ₹1,000 item has a 10% discount, the taxable value is ₹900 and 18% GST on it is ₹162. Enter the discounted price in the calculator.
Why do I see CGST and SGST, and not just GST?
When you sell to a customer in your own state, the tax is shared between the Centre (CGST) and the state (SGST), half each. When you sell to another state, the whole tax is charged as IGST. The total tax is the same either way. Pick 'Same state' or 'Another state' to see both.
Which GST rate applies to my product or service?
It depends on what you sell, and the GST Council changes rates from time to time, so we do not guess. Look up your HSN code (goods) or SAC code (services) in the rate schedules on the CBIC GST site, or ask your accountant. Then type that rate in the box.
Do I have to charge GST if my sales are small?
Only registered businesses charge GST. In most states, a supplier of goods does not have to register until yearly sales pass ₹40 lakh, and a supplier of services until ₹20 lakh (lower limits apply in some states, and some sales, such as inter-state supply of goods, need registration earlier). Check the current limits on the GST portal.
Why is the total a paisa away from the price I typed?
When GST is taken out of a price and then split into two halves, each half is rounded to the nearest paisa, so the parts can add up to a paisa more or less than the number you started with. Invoices do the same rounding, which is why the calculator shows it instead of hiding it.
Checked against the official sources
Last reviewed on 11 October 2026. Tax rules and limits change, and we cannot see your whole situation, so treat this page as a guide, not advice. If something here looks out of date, the official pages below are the ones to trust, and we would be grateful if you told us.
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