Reverse GST Calculator
Work backwards from a final, GST-inclusive price to find the base price, the GST amount, and the CGST/SGST or IGST split — useful for checking bills and invoices.
Find the Base Price
When to Use a Reverse GST Calculation
Reverse GST calculations are useful when you know what a customer paid but need to record the taxable value and tax separately for your books — for instance, when reconciling a cash sale or checking a supplier's bill.
Formula: Base Amount = Final Amount × 100 ÷ (100 + Rate)
Example
A retailer's final bill reads ₹5,900 with 18% GST already applied.
| Final Amount | GST Rate | Base Amount | GST Charged |
|---|---|---|---|
| ₹5,900 | 18% | ₹5,000 | ₹900 |
| ₹2,240 | 12% | ₹2,000 | ₹240 |
Frequently Asked Questions
Yes, they're unrelated. "Reverse GST calculation" here just means working backward from a final price to find the base price. GST reverse charge is a separate compliance mechanism where the buyer, not the seller, pays GST directly to the government.
Check the invoice or receipt for the rate — it's usually printed alongside the tax amount. If unsure, compare the result against a known rate slab (5%, 12%, 18% or 28%) using the buttons above.