Reverse GST Calculator

Reverse GST calculation (also called "GST-inclusive" or "GST-backward" calculation) finds the original base price and the GST component from a total price that already includes GST. Formula: Base Price = Total ÷ (1 + Rate ÷ 100). For example, if you paid ₹11,800 including 18% GST: Base = 11800 ÷ 1.18 = ₹10,000, GST = ₹1,800.

Reverse GST calculation is needed when: (1) You received a GST-inclusive quote and want to know the base price. (2) You need to separate the GST amount from a total for accounting. (3) You want to verify if the GST on a received invoice is correct. (4) You need to calculate ITC you can claim from a purchase.

Base Price = Total Price ÷ (1 + GST Rate ÷ 100). GST Amount = Total Price − Base Price. For intra-state: CGST = SGST = GST Amount ÷ 2. For inter-state: IGST = GST Amount. Example for 18% GST: Base = Total ÷ 1.18.

The total GST extracted is the same. The difference is how it splits: intra-state supply → CGST and SGST each get half the GST amount. Inter-state supply → the full amount is IGST. The base price and total GST are identical in both cases.

The forward GST calculator starts with a base price and adds GST to find the total. The reverse calculator starts with the total (GST included) and extracts the base price and GST. Our GST Calculator handles both modes — use "Add GST to price" for forward and "GST included in price" for reverse.

Yes. If a vendor gives you a total of ₹11,800 claiming it includes 18% GST, reverse-calculate to verify: 11800 ÷ 1.18 = 10,000 base + 1,800 GST. If the invoice shows a different breakdown, the vendor has made an error and you should request a corrected invoice.