About this tool

GST Reverse Calculator

Extract base price and GST from a GST-inclusive amount across every Indian GST slab.

GST Reverse Calculator works backwards from a GST-inclusive amount to show the taxable value and the GST hidden inside it. Pick any Indian slab — 0%, 0.25%, 3%, 5%, 12%, 18% or 28% — or type a custom rate, and it splits the tax into CGST plus SGST for intra-state supply or a single IGST line for inter-state supply. Useful for anyone who has an MRP or a paid amount but needs the pre-tax figure for books, invoices or input tax credit.

How to use GST Reverse Calculator

1. 1

   Open GST Reverse Calculator on AltFTool — it loads instantly in your browser.

2. 2

   Enter the values you already know.

3. 3

   Fine-tune the options to match your scenario.

4. 4

   Read the result and use it in your planning or reporting.

Why use GST Reverse Calculator

• Every slab covered

  All notified GST rates plus a custom-rate box for cess-style or legacy percentages.

• Correct CGST/SGST split

  Intra-state tax is halved to the paise with the rounding difference kept in the SGST line so the total always ties back.

• Side-by-side slab table

  See what the same inclusive amount would break into at every other rate, so a wrong slab is obvious.

Common use cases

• Split a GST-inclusive MRP or restaurant bill into base price and tax before recording it in your books.
• Work out the taxable value to enter on a GSTR-1 line when a customer paid you a round inclusive figure.
• Check the CGST/SGST halves on an intra-state purchase invoice against what the supplier charged.

Frequently asked questions