How to use the GST Invoice Calculator
- Select the supplier's state and the place of supply.
- Add each item with quantity, rate (excl. GST), discount and GST rate.
- Read the totals and tax summary, or download the calculation as a PDF.
Formula
Line taxable value = Quantity × Rate × (1 − Discount ÷ 100)
Line GST = Taxable value × GST rate ÷ 100
Invoice total = Σ taxable values + Σ GST (± round-off)
Line-by-line tax
On an invoice with mixed rates, GST is worked out for each line on its taxable value (after discount), then added up by rate. The tax summary groups the taxable value and tax for each rate, which is also how it's reported in returns.
Worked example
2 × ₹1,000 @ 18%, 3 × ₹499.50 @ 5%, 1 × ₹250 @ 18%, same state
- 18% group: ₹2,250 taxable, ₹405 GST
- 5% group: ₹1,498.50 taxable, ₹74.93 GST
- Total = ₹3,748.50 + ₹479.93 = ₹4,228.43
₹4,228 after round-off (−₹0.43)
Important notes
- Each line's tax is rounded to the paisa, so totals match what you'd print on the invoice.
Frequently asked questions
Can one invoice have items at different GST rates?
Yes. Each item carries its own rate, and the invoice shows the tax for each.
Is round-off allowed on a GST invoice?
Rounding the invoice total to the nearest rupee is common practice. The tax itself is calculated to the paisa.
Sources and review
Last reviewed on by the BizToolsIndia editorial team. Official references:
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