When a price already includes GST, working out the original amount by hand is fiddly. This free reverse GST calculator does it instantly — enter a GST-inclusive total and the rate (5%, 12%, 18% or 28%) and it shows the base amount and the GST portion separately.
Perfect for invoicing, bookkeeping and quick checks.
Why use this reverse gst calculator?
Removes GST instantly
Splits any inclusive price into base + GST.
All Indian slabs
Works with 5%, 12%, 18%, 28% or a custom rate.
Clear breakdown
See CGST/SGST split and the exact tax amount.
Free & instant
No signup — calculate as many as you need.
How to use it
- Enter the total, GST-inclusive amount.
- Choose the GST rate (or type a custom one).
- Read the base amount and the GST portion instantly.
- Use the CGST/SGST split for your invoice or books.
Popular use cases
- Freelancers and businesses raising GST invoices.
- Extracting tax from an all-inclusive quoted price.
- Accountants and shop owners doing quick checks.
- Verifying the GST on a bill or receipt.
Frequently asked questions
How does a reverse GST calculation work?
Base amount = inclusive amount ÷ (1 + rate/100). The GST portion is the inclusive amount minus the base. This tool does it for you.
What are the GST rates in India?
The common slabs are 5%, 12%, 18% and 28%. You can also enter a custom rate.
What is CGST and SGST?
For intra-state sales, GST is split equally into CGST (central) and SGST (state). So 18% GST is 9% CGST + 9% SGST.
Is this an official calculator?
It is a free helper for quick calculations. For filing, always confirm with your accountant or the GST portal.
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