Free GST calculators
Three small calculators that run entirely in your browser — no sign-up, no email, nothing stored. Use them for a quick check, then reach for BillBook when you need the actual invoice.
GST calculator
Add GST to an amount, or pull the GST out of a GST-inclusive amount, at any rate from 0% to 28%.
Open calculatorCGST & SGST calculator
For sales inside your own state: see the taxable value and the equal CGST and SGST halves.
Open calculatorIGST calculator
For sales to another state or union territory: see the taxable value and the single IGST amount.
Open calculatorGST rates and rules change. Please verify current rules with official government sources or your CA before filing.
Need the whole invoice, not just the tax?
BillBook does this maths per line item, applies CGST/SGST or IGST from the place of supply, and gives you a downloadable tax-invoice PDF — for ₹299 once.
Get Lifetime Access for ₹299