Invoice GST breakdown calculator
Break a GST amount into taxable value, CGST, SGST, or IGST — reading a tax-inclusive total backwards or building a tax-exclusive one forwards, and seeing what the same number is worth either way.
- Taxable value
- ₹10,000
- Total GST at 18%
- ₹1,800
- CGST at 9%
- ₹900
- SGST at 9%
- ₹900
- GST as a share of the total
- 15.25%
- Check: base + GST
- ₹11,800
Read the other way, that same ₹11,800 becomes an invoice total of ₹13,924, a ₹2,124 difference from adding the tax instead of removing it. That gap is the reason to be explicit about which figure is being quoted: an inclusive amount already contains the tax and an exclusive one does not, so they are not the same number with a label attached.
How this is calculated: base = total ÷ (1 + rate) for a tax-inclusive amount, and total = base × (1 + rate) for a tax-exclusive one. CGST and SGST are each charged at half the slab rate on an intra-state supply, and IGST at the full slab rate on an inter-state supply, so the total tax is identical either way and the toggle only changes which lines appear on the invoice. The amount and slab are the reader’s own inputs, and the slab that actually applies depends on the HSN/SAC classification of the supply, so treat this as arithmetic on those inputs and confirm the final breakup with a CA.
Need the breakup on the invoice itself?
NoxOrigin issues GST invoices with HSN/SAC lines, place-of-supply aware CGST/SGST versus IGST treatment, and a tax summary that ties back to the taxable value — so the calculator above is a check on the numbers rather than a substitute for the invoice.
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