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.
Rates as of 12 October 2026. From 22 September 2025 the GST Council replaced the 12% and 28% slabs for most goods and services with a 5% merit rate and an 18% standard rate, and added a 40% rate for a select few goods and services. A few items carry special rates (the list also has 3%, and a few precious-stone items have lower rates such as 0.25% or 1.5%), and compensation cess can still apply to a small set of goods such as tobacco products. Check the notification for your item. 12% and 28% are still listed because they apply to invoices dated before 22 September 2025. Source: GST Council, 56th meeting press release (PIB), 3 September 2025. The right rate depends on the HSN or SAC code of what you sell; confirm it with your CA.
Stop calculating by hand.
BillForge creates GST invoices with the tax already worked out — gap-free Rule 46 numbering, GSTR-1 & 3B export, TDS records. Free for 3 months, no card needed. Your CA should still review what you file.
Start free for 3 monthsFrequently 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.