Calculate GST online
₹1,000.00
Base amount
₹180.00
GST amount
₹1,180.00
Total amount
Whether you're pricing a product or checking an invoice, this tool calculates GST both ways — add GST to a base price to get the final amount, or work backward from a GST-inclusive amount to find the base price and tax component. Pick a standard GST slab (5%, 12%, 18%, 28%) and see results update instantly, entirely in your browser.
Adding versus removing GST
These are different calculations and mixing them up is a common invoicing error. Adding GST starts from a base price and multiplies up. Removing GST starts from a total that already includes tax and divides back down — which is not the same as subtracting the percentage. Removing 18 percent GST from ₹1,180 gives a base of ₹1,000, not ₹967.60, because the 18 percent was calculated on the base, not on the total.
CGST, SGST, and IGST
The rate shown here is the total. For a transaction within one state, that total splits equally into CGST and SGST — 18 percent becomes 9 percent each on the invoice. For inter-state transactions it appears as a single IGST line at the full rate. The amount payable is identical either way; the split determines which government receives it and how it is reported.
Choosing the right rate
GST slabs depend on the goods or service category, and getting the rate wrong on invoices creates reconciliation problems later. The common slabs are 5, 12, 18, and 28 percent, with some items zero-rated or exempt. If you are unsure which applies to what you sell, confirm against the current rate schedule or with an accountant rather than guessing — this calculator does the arithmetic once you know the rate.
Frequently asked questions
- What's the difference between adding and removing GST?
- "Add GST" starts from a base price and calculates the GST-inclusive total. "Remove GST" starts from a GST-inclusive amount (like an invoice total) and works backward to find the base price and tax.
- Which GST slab should I use?
- This depends on the goods or service category under Indian GST law — common slabs are 5%, 12%, 18%, and 28%. Check the applicable rate for your specific product or service.
- Is my data sent anywhere?
- No, calculation happens locally in your browser using JavaScript. Nothing is transmitted.
- Why is removing GST not just subtracting the percentage?
- The tax was calculated on the base amount, not the total. Removing it requires dividing by 1 plus the rate, which is what this tool does.
- Should I use CGST plus SGST or IGST?
- CGST and SGST split equally for transactions within a state; IGST at the full rate for inter-state. The total payable is the same.