How the GST Calculator Works
GST (Goods and Services Tax) is added on top of a product or service's base price at one of four standard slabs in India — 5%, 12%, 18%, or 28%, depending on the category. This calculator handles both directions: working out how much GST to add to a price that doesn't yet include it, or working backward from a GST-inclusive price to find the original base amount and the tax portion within it.
Select Add GST when your amount is the base price
before tax — the calculator multiplies it by the GST rate to find
the tax, then adds the two together for the total. Select
Remove GST when your amount already includes GST
(like a receipt total or an invoice) — the calculator divides it by
(1 + rate/100) to back out the base price, then the
difference is the GST portion.
This is useful for shopkeepers pricing products, freelancers raising GST-inclusive invoices, or anyone who wants to double-check the tax breakdown on a bill. The math is exact — enter the correct slab for your goods or service and the base amount, GST amount, and total will always add up correctly.
Frequently Asked Questions
What are the GST slabs in India?
India uses four main GST slabs — 5%, 12%, 18%, and 28% — plus a 0% exempt category for essential goods. The rate depends on the type of product or service; check your invoice or the government's GST rate schedule if you're unsure which slab applies.
What's the difference between "Add GST" and "Remove GST"?
Use "Add GST" when you have a base price and want to know the final price after tax. Use "Remove GST" when you have a final, tax-inclusive price (like a shop receipt) and want to see the original base price and how much of the total was tax.
Does this calculator account for CGST and SGST separately?
No — it calculates the total GST amount only. For intra-state transactions this is typically split evenly between CGST and SGST (e.g. an 18% rate becomes 9% CGST + 9% SGST); for inter-state transactions it's charged as IGST in full. The total tax amount is the same either way.