Reverse GST Calculator
Got a price that already includes GST? Enter the gross amount and the rate to pull out the base (taxable) value and the GST hidden inside it.
Stop calculating by hand.
BillForge creates GST-compliant invoices with the tax already worked out — gap-free Rule 46 numbering, GSTR-1 & 3B export, TDS certificates. Free for 3 months, no card needed.
Create GST-compliant invoices freeFrequently asked questions
How do you reverse-calculate GST from a total?
Divide the GST-inclusive amount by (1 + rate ÷ 100) to get the base. The GST is the gross minus the base. For example, ₹11,800 at 18%: base = 11,800 ÷ 1.18 = ₹10,000, and GST = ₹1,800.
When do I need a reverse GST calculation?
When a price is quoted as 'inclusive of GST' and you need the taxable value for accounting, GSTR-1, or input tax credit. It is also useful for MRP-based retail where the displayed price already contains GST.
Does the reverse split into CGST, SGST and IGST too?
Yes. Once the base is extracted, the same same-state (CGST+SGST) or other-state (IGST) split applies. Choose your supply type and the calculator shows each component.
Is the extracted base rounded?
Yes, to two decimal places (paise), using the same banker-safe rounding BillForge applies on real invoices, so the figures tie back exactly to a GSTR-1 line.