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GST Calculator

Calculate GST-inclusive and GST-exclusive totals.

How This Tool Works

The GST Calculator handles both directions of Goods and Services Tax arithmetic. Enter a net (pre-tax) price and a GST rate to get the tax-inclusive total. Or enter a gross (tax-inclusive) price to extract the GST component and the original net price. The formula for adding GST is Gross = Net × (1 + Rate/100). To remove GST from an inclusive price, divide by (1 + Rate/100) — never subtract the percentage directly, which is the most common mistake.

How to Use

  1. Enter the price in field A (net price if adding GST, gross price if removing GST).
  2. Enter the GST rate in field B — common rates are 5%, 12%, 18%, and 28% for India; 10% for Australia; 15% for New Zealand.
  3. Click Run. The result shows the GST amount and the final inclusive or exclusive price.
  4. For Indian users: choose the correct slab (5% for packaged food, 18% for most services, 28% for luxury goods).

Common Questions

What is the difference between GST-inclusive and GST-exclusive?

GST-exclusive (net) price is the base price before tax. GST-inclusive (gross) price already contains the tax. On an invoice, you add GST to the net price. When a customer asks for the pre-tax price of an inclusive amount, you divide by (1 + rate).

Why can't I just subtract 10% from the gross to get the net?

Because GST is calculated on the net price, not the gross. On a $110 inclusive price at 10% GST, the net is $100 — not $110 − $11 = $99. The correct formula is $110 ÷ 1.10 = $100.

Does India have a single GST rate?

No. India uses a multi-slab GST system: 0% (fresh produce, essentials), 5% (packaged food, small restaurants), 12% (processed food, computers), 18% (most manufactured goods, services), and 28% (luxury goods, tobacco, automobiles).

Read the full guide →