How to calculate GST
Enter an amount and pick the GST rate for your product or service — 5%, 12%, 18%, 28%, or a custom rate. Choose "Add GST" if your amount is the base price before tax, or "Remove GST" if it's already the final price and you need to work backward to find the base amount and tax portion. Pick intra-state or inter-state to see the tax split as CGST+SGST or as a single IGST line.
This is built for the moment a quote, invoice, or bill only shows one number and you need the other — a freelancer confirming what to charge on top of a quoted rate, a shopper working out whether a "GST included" price is actually cheaper than a competitor's "plus GST" price, or a small business owner double-checking an invoice's CGST/SGST split before filing. Because everything runs in your browser as plain arithmetic, there's no daily limit, no account, and no delay — you get the breakdown as you type.
How do I calculate GST on an amount?
If you have a base amount and want to add GST, multiply it by the GST rate and add that to the original amount — for example, ₹1,000 plus 18% GST is ₹1,000 + ₹180 = ₹1,180. This calculator does that instantly: enter the amount, pick the rate, and switch to "Add GST" mode.
What's the difference between GST-inclusive and GST-exclusive amounts?
A GST-exclusive amount is the base price before tax is added. A GST-inclusive amount already has GST baked in — the total a customer actually pays. If you only have the final inclusive price and need the base amount and tax split, use "Remove GST" mode rather than just multiplying by the rate again, since that would overcharge the tax portion.
What is the difference between CGST+SGST and IGST?
For a sale within the same state, GST splits evenly into CGST (Central) and SGST (State) — each at half the total rate, so 18% becomes 9% + 9%. For a sale between two states, the full rate is charged as a single IGST instead, with no split. The total tax amount is identical either way; only how it's divided changes.
Which GST rate applies to my product or service?
GST rates in India are set per category by the GST Council — most goods and services fall into the 5%, 12%, 18%, or 28% slabs, though some items are taxed at 0% or fall outside GST entirely. This calculator doesn't look up rates for you; check the applicable slab for your specific product (your invoice, supplier, or the GST portal will usually confirm it) and select it here.
Is my amount or business data stored anywhere?
No — every calculation happens locally in your browser using plain JavaScript. Nothing you type is sent anywhere or saved once you leave the page.