How do I remove GST from a total amount?

Divide the GST-inclusive amount by (1 + GST rate/100). For ₹1,180 at 18% GST: 1180 / 1.18 = ₹1,000 base price and ₹180 GST.

What is the reverse GST formula?

Base amount = Total / (1 + rate/100). GST amount = Total − Base amount. For 18% GST the divisor is 1.18, for 5% it is 1.05, and for 40% it is 1.40.

Why do I need a reverse GST calculation?

When a price is quoted inclusive of GST — like an MRP or a customer quote — you must back-calculate the taxable value to raise a correct invoice, record it in books, and report it in GSTR-1 and GSTR-3B.

Is the reverse GST calculation different for IGST?

No. The base amount is the same. For interstate supply the entire tax shows as IGST; for intrastate it splits equally into CGST and SGST.

Reverse GST Calculator

Remove GST from a price that already includes it. Enter the total, get the taxable value and tax breakup. No sign-up required.

Total amount (including GST)GST Rate (%)Interstate supply (IGST instead of CGST + SGST)

How Reverse GST Calculation Works

A reverse GST calculation (also called GST-inclusive or back-calculation) extracts the tax from a price that already includes GST. This is what you need when a customer quote, MRP, or receipt shows only the final amount.

The Formula

Base amount = Total ÷ (1 + GST rate ÷ 100)
GST amount = Total − Base amount

Example: a ₹1,180 bill at 18% GST → base = 1180 ÷ 1.18 = ₹1,000, GST = ₹180. For intrastate supply that splits into ₹90 CGST + ₹90 SGST; for interstate it is ₹180 IGST.

When You Need It

Raising a tax invoice from a GST-inclusive quote or MRP
Recording GST-inclusive expenses correctly in your books
Reporting taxable value (not the gross amount) in GSTR-1 and GSTR-3B
Checking a vendor's invoice where the tax split looks wrong

Need to add GST on top of a base price instead? Use the GST calculator. Not sure which rate applies? Try the HSN code finder.