What is GST Calculator?
The GST Calculator works out Goods and Services Tax on any amount in both directions. Add GST to a base price to get the final invoice value, or remove GST from a price that already includes it to find the taxable value. It supports all standard Indian GST slabs - 0.25%, 3%, 5%, 12%, 18%, and 28% - along with any custom rate, and splits the tax into CGST and SGST for intra-state supply or IGST for inter-state supply.
How to Use
Choose Add GST if your amount is exclusive of tax, or Remove GST if it already includes tax.
Enter the amount and pick a GST rate, or type your own rate.
Select intra-state or inter-state supply to see the CGST/SGST or IGST breakdown.
Why Use This Tool?
Reverse GST calculation trips people up - dividing an inclusive price by the rate gives the wrong answer, because the tax is charged on the base value, not the total. This tool applies the correct formula both ways and shows the component split you need for invoices and GSTR filings. It runs entirely in your browser, so your billing figures never leave your device.
FAQ
Divide the inclusive amount by (100 + GST rate) and multiply by 100. For example, ₹11,800 at 18% GST gives a base of ₹10,000 and tax of ₹1,800. Simply taking 18% of ₹11,800 would overstate the tax - the Remove GST mode handles this for you.
For a supply within the same state, the tax is split equally into CGST (central) and SGST (state) - 18% GST becomes 9% CGST plus 9% SGST. For a supply between two different states, the full amount is charged as IGST instead.
Rates depend on the HSN or SAC code of what you are selling. 5%, 12%, 18%, and 28% are the main slabs, with 0.25% and 3% applying to items such as rough diamonds and gold. Check the official CBIC rate finder if you are unsure.
Yes. The base value, tax amount, and component split shown here are the figures you need for a tax invoice. This tool is a calculator, though - it does not file returns or generate invoice documents.
No. The calculation runs entirely in your browser and nothing is sent to any server.