GST Calculator: Add and Remove Tax
Published July 16, 2026By Samson PG
Inclusive price ÷ (1 + rate) recovers the base; base × rate is the tax. Here is add-GST and remove-GST in one place.
GST (Goods and Services Tax) is usually a percentage of the taxable value. You either add GST to a pre-tax amount or remove GST from a tax-inclusive price.
Illustrative tax math only — not tax, legal, or filing advice. Rates and exemptions change; verify with official sources.
Add GST (tax-exclusive → inclusive)
GST amount = base × (rate ÷ 100)
inclusive = base + GST amountExample: base ₹1,000, rate 18% → GST ₹180 → inclusive ₹1,180.
Remove GST (inclusive → base)
base = inclusive ÷ (1 + rate ÷ 100)
GST = inclusive − baseExample: inclusive ₹1,180 at 18% → base = 1180 ÷ 1.18 = ₹1,000, GST ₹180.
Common rate quick view
| Rate | Multiplier to add | Divide inclusive by |
|---|---|---|
| 5% | × 1.05 | ÷ 1.05 |
| 12% | × 1.12 | ÷ 1.12 |
| 18% | × 1.18 | ÷ 1.18 |
| 28% | × 1.28 | ÷ 1.28 |
CGST / SGST / IGST split
On intra-state supplies, the headline rate is often split (e.g. 9% + 9% for 18%). The total still matches the combined rate; the split is a reporting detail.
Privacy
Invoice figures stay in your browser.
Use TryCalculatingNow GST Calculator
TryCalculatingNow GST Calculator adds or removes GST for common slabs. For VAT-style inclusive/exclusive math in other regions, see TryCalculatingNow VAT Calculator and the sibling guide VAT vs GST basics.
FAQ
Is MRP always GST-inclusive?
Often retail prices are inclusive — still confirm the invoice breakup.
Can I just multiply by 0.18 on an inclusive price?
No — that overstates tax. Divide by 1.18 first.
Does GST apply to every item?
No. Exemptions and special rates exist.
What about discounts before tax?
Taxable value rules depend on whether discount is pre- or post-supply — follow invoice norms, not a blog shortcut.