Add GST to a base price or reverse-calculate (remove) the GST hidden inside an inclusive amount — at every current GST 2.0 slab (in force since 22 September 2025): 5%, 18%, 40%, plus 3% on gold and silver, 0.25% on rough diamonds, or any custom rate — including the abolished 12% and 28% for legacy invoices. The calculator automatically splits the tax into CGST + SGST for sales within your state or a single IGST for inter-state sales, and gives you a one-click copyable, invoice-ready breakdown. Reverse calculation is the one that trips people up: to extract 18% GST from ₹11,800 you divide by 1.18 (₹10,000 base + ₹1,800 GST) — simply subtracting 18% gives the wrong answer. Free, instant, no signup. E-commerce sellers can also use our marketplace fee calculator, which includes the 18% GST charged on Amazon, Flipkart and Meesho seller fees.