GST Calculator

Overview

A GST calculator for Indian tax arithmetic: add GST to a net price, or reverse-calculate the GST inside a gross price. It ships one-click buttons for familiar slab rates and shows the net, GST, and gross amounts together, plus how the tax splits under the CGST/SGST versus IGST conventions.

How It Works

Enter an amount, click one of the slab preset buttons (0% exempt, 3% gold, 5%, 18%, or 40% demerit) or type any custom rate from 0 to 100 into the small rate field, and read the three outputs: net, GST at the chosen rate, and gross. Pick Intra-state to see the tax split into CGST and SGST halves, or Inter-state to see the full rate as IGST. Tick the checkbox labelled 'Amount already includes GST' to switch to reverse calculation — the tool then extracts the net and the embedded tax from your gross figure. A dated note under the results states exactly which slab structure and effective date the tool uses, so you can tell at a glance whether it is current.

Step-by-Step Usage Guide

1. Choose whether your amount excludes GST (net) or already includes it (gross).
2. Click a slab preset or type the exact rate that applies to your supply.
3. Read the net, GST, and gross amounts in the results row.
4. Check the note beneath for the CGST/SGST split if the supply is intra-state.

Technical Specifications & Standards

The forward calculation is gross = net × (1 + rate/100). The reverse mode uses the mathematically correct divisor form, net = gross / (1 + rate/100), rather than subtracting rate percent of the gross — a distinction that matters, because extracting 18% from 1,180 gives a net of 1,000 and tax of 180, while deducting 18% of the gross would wrongly report 212.40. The supply-type toggle is presentational arithmetic: India's GST law splits a full rate into equal CGST and SGST halves for supplies within a state and charges the full rate as IGST between states, and the tool displays the actual amounts either way. About the presets: the buttons follow the GST 2.0 structure that took effect on 22 September 2025 — 0% exempt, 3% for gold and jewellery, 5% and 18% as the two main slabs, and 40% on specified demerit goods such as pan masala, aerated beverages, and luxury vehicles. The former 12% and 28% slabs were withdrawn on that date; niche rates outside the five buttons (0.25% rough diamonds, and the deferred 40% transition for tobacco) go in the custom rate field. Verify your product's slab on official CBIC or GST Council sources before invoicing — the dated note in the tool records the structure it uses so mismatches are visible rather than silent.

Targeted Use Cases

• Pricing a product by adding GST to a net margin you want to protect.
• Extracting the taxable value from a tax-inclusive MRP for accounting.
• Comparing the GST component on an intra-state versus inter-state invoice.
• Sanity-checking a supplier's quoted tax-inclusive price against your own arithmetic.

Notes & Gotchas

• If your supply carries a niche notified rate that is not one of the five buttons, type it into the custom field — the arithmetic accepts any rate.
• Use the inclusive toggle whenever a price is quoted as tax-included, or the split will be wrong.
• Remember the reverse mode divides by (1 + rate); never subtract the rate percent from the gross.
• For filed invoices, confirm the HSN-wise rate on official GST sources — this tool is arithmetic, not tax advice.

Frequently Asked Questions