GST Calculator + Invoice Generator

GST in India is split into three components depending on where the buyer and seller are located. For intra-state supplies (buyer and seller in the same state), the GST is split equally — CGST goes to the central government, SGST goes to the state government. So 18% GST becomes 9% CGST + 9% SGST. For inter-state supplies (different states, or exports), a single IGST is charged at the full rate (e.g. 18% IGST), which the central government later apportions to the destination state. Place of supply, not billing address, decides which tax applies — get the GSTIN state code right or you will short-pay one tax and over-pay another.

Exclusive means the price you quote is the pre-GST taxable value, and GST is added on top — ₹10,000 at 18% becomes ₹10,000 + ₹1,800 = ₹11,800 invoice total. Inclusive means the price already includes GST and you back it out using the formula GST = price × rate / (100 + rate) — ₹11,800 inclusive at 18% gives ₹1,800 GST and ₹10,000 net. B2B invoices are conventionally exclusive (so the buyer can see and claim ITC clearly); retail / B2C is usually quoted inclusive. Both modes in this calculator give identical CGST/SGST/IGST splits — only the headline number differs.

HSN (Harmonized System of Nomenclature) codes classify goods; SAC (Services Accounting Code) codes classify services. Every GST invoice must mention these. As of FY 2025-26, businesses with turnover above ₹5 crore must use 6-digit HSN/SAC; below ₹5 crore, 4 digits suffice (and exempt B2C below ₹1.5 Cr can skip them entirely). Common examples: 998314 = IT consulting services, 998313 = IT support services, 8517 = mobile phones, 1006 = rice. The line-item table on this tool accepts any code — confirm your product code on the official CBIC HSN/SAC finder before filing.

India has four main GST rate slabs: 5% (essentials — packaged food, footwear under ₹1,000, basic apparel, transport), 12% (standard goods — processed food, butter, mobile phones, business-class air travel), 18% (most services and goods — restaurants, IT services, telecom, financial services, branded apparel above ₹1,000), and 28% (luxury and sin goods — cars, ACs, refrigerators, soft drinks, tobacco, with a cess on top). A small set of items are zero-rated (exports, fresh produce) or exempt (healthcare, education, residential rent). The CBIC publishes rate notifications periodically — check before billing high-value items.

E-invoicing on the Invoice Registration Portal (IRP) is mandatory for any business with aggregate turnover above ₹5 crore in any previous year from FY 2017-18 onward (the threshold has dropped progressively from ₹500 Cr in 2020 to ₹5 Cr in August 2023). Eligible invoices must carry an IRN (Invoice Reference Number) and signed QR code from the IRP before they are valid. This tool does not generate IRN — it produces the underlying tax invoice in the correct format, but you still need to push it through the IRP (or a GSP/ASP) to get the IRN and QR. For sub-₹5 Cr businesses, this invoice is fully valid as-is.

Nothing leaves your browser. The calculation, invoice generation, and HTML download all run entirely client-side — no server call, no cookie, no analytics on your inputs, no copy stored anywhere. Refresh the page and the values reset to the example invoice. The downloaded HTML file is yours to keep, archive, or share.