GST Calculator
Add GST to a price, or work backwards from a bill that already includes it. The CGST, SGST and IGST split is worked out for you. Nothing is uploaded.
How to use it
- Type the amount you are working with.
- Say whether that amount is before GST or after it. This one dropdown is the whole difference between adding tax and removing it.
- Pick the slab, then choose whether the sale stays inside one state or crosses a border, to see the split the invoice needs.
Adding GST and removing GST are different sums
Adding is the easy direction: 1,000 at 18% means 180 of tax and a total of 1,180. Going the other way trips people up. Given a bill of 1,180, many people take 18% off it and get 967.60. That is wrong, because the 18% was charged on the base amount, not on the total.
The correct sum divides instead of subtracting: 1,180 divided by 1.18 gives 1,000, and the tax is the 180 left over. The calculator shows the working under the big number so you can check it against a bill line by line.
CGST, SGST and IGST
The rate never changes because of where the buyer is; only the way it is written on the invoice changes. Sell within your own state and 18% appears as 9% CGST plus 9% SGST, one half to the centre and one half to the state. Sell to another state and the same 18% appears as a single IGST line. Either way the buyer pays the same amount.
Which slab applies to my product?
The September 2025 revision simplified the structure: most goods and services now sit at 5% or 18%, with 0% for exempt items and 40% for a short list of luxury and sin goods. The old 12% and 28% slabs are kept in the dropdown because invoices raised before the change still carry them.
Rates are set per item against an HSN or SAC code, and they do get revised. This page does the arithmetic; it cannot know which rate your particular product attracts. Confirm the rate against the official CBIC rate finder or with your accountant before you put a number on a real invoice.
Frequently asked questions
How do I remove GST from a total?
Set the second dropdown to After GST and enter the amount printed on the bill. The calculator divides by one plus the rate, so a total of 1,180 at 18 percent gives a base of 1,000 and GST of 180. Subtracting 18 percent from the total instead is the common mistake, and it gives 967.60, which is wrong.
What are the current GST slabs in India?
Since the September 2025 revision most goods and services sit at 5 percent or 18 percent, with 0 percent for exempt items and 40 percent for a short list of luxury and sin goods. The older 12 percent and 28 percent slabs are still offered here, because invoices raised before the change carry them and old bills still have to be checked.
What is the difference between CGST, SGST and IGST?
When the buyer and the seller are in the same state the tax is split in half between the centre and the state, and the bill shows it as CGST and SGST. When the sale crosses a state border the whole amount goes to a single IGST line instead. The total tax you pay is identical either way.
Is anything I type sent anywhere?
No. The arithmetic happens in JavaScript inside your own browser. Nothing is uploaded and nothing is saved - close the tab and it is gone.