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GST Calculator

Add GST to a price, or work backwards from a GST-inclusive total to find the taxable value. Pick your slab, choose whether the amount you have already includes tax, and the calculator splits the result into CGST and SGST for a sale within your state, or IGST for one across state lines.

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How to use GST Calculator

  1. Enter the amount you are working with.

  2. Say whether that amount is before GST or already includes it — this is the step people get wrong.

  3. Pick the applicable slab: 0%, 5%, 12%, 18% or 28%.

  4. Tick 'inter-state supply' if the buyer is in a different state, and read your CGST/SGST or IGST split.

The mistake that costs businesses real money

Extracting GST from an inclusive amount requires dividing by one plus the rate, not subtracting the rate. To remove 18 percent GST from ₹1,180, you divide by 1.18 and get a taxable value of ₹1,000, leaving ₹180 of tax. Subtracting 18 percent of ₹1,180 instead gives ₹967.60 — wrong by over ₹32 on a single small invoice.

The error is systematic rather than random: it always understates the taxable value and overstates the tax. Repeated across a year of invoices it produces returns that do not reconcile, and the discrepancy tends to surface during an audit rather than during the month it was made.

It is also entirely avoidable, which is why this calculator asks explicitly whether your amount includes GST rather than guessing. Choosing the right mode is the whole job; the arithmetic after that is automatic.

CGST, SGST and IGST in practice

For a supply within your own state, GST splits evenly between the centre and the state: 18 percent becomes 9 percent CGST plus 9 percent SGST, shown as separate lines on the invoice. For a supply to another state, the full 18 percent is charged as IGST on a single line.

The customer pays the same total either way, so the split feels like paperwork. It is not: getting it wrong is a common cause of mismatched returns, because the recipient claims input credit under a head that does not match what you declared.

Which applies is determined by the place of supply, which is not always the customer's billing address — for services in particular, the rules can point elsewhere. If you supply across state lines regularly, the place-of-supply provisions are worth reading properly once rather than inferring each time.

Rates, registration and the composition scheme

The five slabs are 0, 5, 12, 18 and 28 percent, and which applies is determined by HSN code for goods or SAC code for services rather than by category name. Broadly, essentials sit at 0 or 5, most services and manufactured goods at 18, and luxury and sin goods at 28 plus cess — but the correct answer for your product is its code, not the general pattern.

Registration generally becomes compulsory above ₹40 lakh turnover for goods or ₹20 lakh for services, with lower thresholds in special-category states, and is mandatory regardless of turnover for inter-state suppliers and e-commerce sellers.

The composition scheme offers small businesses a flat low rate on turnover with much simpler filing, at the cost of not being able to claim input credit or charge GST on invoices. That second limitation matters commercially: business customers who want input credit will prefer a supplier who can give it to them.

Frequently asked questions

How do I remove GST from an inclusive price?

You divide, you do not subtract. To strip 18% GST from a ₹1,180 total, divide by 1.18 to get a taxable value of ₹1,000, leaving ₹180 of GST. Subtracting 18% of ₹1,180 instead gives ₹967.60, which is wrong by more than ₹32 — a mistake that compounds badly across a year of invoices. Choosing 'Including GST' on this page applies the correct method automatically.

What is the difference between CGST, SGST and IGST?

For a sale within your own state, GST is split evenly between the centre and the state: an 18% rate becomes 9% CGST plus 9% SGST. For a sale to another state, the whole 18% is charged as a single IGST, which the centre later apportions. The total the customer pays is identical either way — only the split on the invoice changes. Getting it wrong is a common cause of mismatched GSTR filings.

Which GST rate applies to my product or service?

The five slabs are 0%, 5%, 12%, 18% and 28%. Broadly: essential foods and healthcare sit at 0% or 5%, processed foods and business-class travel at 12%, most services and manufactured goods at 18%, and luxury or 'sin' goods such as cars, tobacco and aerated drinks at 28% plus cess. Because classification is decided by HSN or SAC code rather than by category name, check your specific code on the CBIC portal — this calculator computes whichever rate you select but cannot choose it for you.

Do I need to register for GST?

In most states registration becomes compulsory once turnover exceeds ₹40 lakh for goods or ₹20 lakh for services, with lower thresholds of ₹20 lakh and ₹10 lakh in special-category states. Registration is mandatory regardless of turnover for inter-state suppliers, e-commerce sellers and businesses under reverse charge. Thresholds change, so confirm current figures before deciding.

What is the composition scheme?

It lets small businesses under ₹1.5 crore turnover pay a flat, low rate on turnover — typically 1% for traders, 2% for manufacturers, 5% for restaurants — with far simpler quarterly filing. The trade-off is real: you cannot claim input tax credit, and you cannot charge GST on your invoices, which makes you less attractive to business customers who want that credit. This calculator computes standard GST, not composition rates.

Can I use this for VAT outside India?

The arithmetic is identical for any single-rate value-added tax, so the add-and-remove calculations work for UK VAT at 20%, EU VAT and similar systems — just type the rate you need. The CGST/SGST split is India-specific, so leave 'inter-state supply' ticked to see a single combined tax line.

Is anything I enter uploaded?

No. Every calculation happens in your browser. No amounts, GSTINs or business details are transmitted or stored, and the page continues to work offline once loaded.

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