GST and VAT calculator
Add tax to a price or pull it back out of a tax-inclusive one, with the CGST/SGST split.
The reverse calculation is a division, not a subtraction
This is the reason most people end up looking for a GST calculator at all. You have a tax-inclusive figure — ₹1,180 including 18% — and you need the amount before tax. The instinct is to take 18% off, which gives ₹967.60. The correct answer is ₹1,000.
The reason is that the 18% was charged on the smaller number, not the bigger one. Going backwards you divide by 1.18, you do not subtract 18% of the total. The gap grows with the rate: at 28% the naive method is out by more than ten per cent, which on an invoice of any size is a real error that ends up in somebody's books.
Because it is such a common mistake, this page shows you what the wrong method would have given, clearly labelled, next to the right answer. If a figure you were given matches that line rather than the correct one, you now know where it came from.
CGST, SGST and IGST
Indian GST arrives as one rate but is split by where the supply goes. A sale within a state is divided equally into CGST, collected centrally, and SGST, collected by the state — so 18% is 9% and 9%. A sale between states is IGST at the whole rate, undivided. The tax the customer pays is identical either way; what changes is the split on the invoice, and getting it wrong is a filing problem rather than a pricing one. Choose the case above and the breakdown appears.
About the rates
The rate is a field you fill in, not a table this page decides for you. That is deliberate. Indian GST slabs have historically been 0, 5, 12, 18 and 28 per cent, with additional cess on some categories, and the structure was reformed in 2025. Rates also change at short notice and depend on the specific HSN classification of what you are selling. A calculator that hard-codes a slab table will eventually be confidently wrong, which is exactly the failure this site was rebuilt to end — so check the rate that applies to your goods and type it in.
It works for VAT and sales tax too
Nothing about the arithmetic is specific to India. Set the split to "do not split" and this handles UK VAT at 20%, EU VAT at whatever your member state charges, Australian GST at 10%, or any sales tax anywhere. The inclusive-to-exclusive division is the same operation and the same common mistake in every country that has a consumption tax.
Quantity
Set a quantity and the tax is worked out on the line total, with the per-unit inclusive price shown as well — which is the figure you want when you are deciding what to put on a price tag.
Common questions
How do I remove GST from an amount?
Divide by (1 + rate ÷ 100). For 18%, divide by 1.18. Do not subtract 18% of the inclusive amount — that undershoots, and by more the higher the rate.
What is the difference between CGST, SGST and IGST?
They are the same total tax, split differently. Within one state it is halved into CGST and SGST; between states it is a single IGST at the full rate. The customer pays the same either way.
Which GST rate applies to my product?
That depends on its HSN classification, and it changes. This calculator takes whatever rate you give it rather than guessing, because a hard-coded slab table goes stale and a wrong rate on an invoice is a real problem.
Can I use this for VAT?
Yes. Set the split to "do not split" and it works for VAT, sales tax or any consumption tax. The inclusive-to-exclusive arithmetic is identical everywhere.
Why does the page show a "common wrong answer"?
Because that figure circulates. If a number you were handed matches it, somebody subtracted the percentage from the inclusive total instead of dividing, and now you can point at where it came from.
Is anything I type stored?
No. It runs entirely in your browser and answers as you type.