GST Calculator

How to Use the Calculator

• Pick a mode at the top. Add GST takes a pre-tax amount and gives you the GST-inclusive total. Remove GST takes an inclusive amount and works backwards to the pre-tax base.
• Enter the amount. In Add mode this is your cost or base price. In Remove mode it is the final invoice value.
• Set a profit ratio if you want. This is optional and is only useful if you are pricing for resale and want to add a margin on top of cost before tax.
• Choose your GST rate. The buttons cover the slabs in use after the GST 2.0 reform of September 2025: 3%, 5%, 18%, and 40%.
• Pick the transaction type. Intra-state splits the tax equally into CGST and SGST. Inter-state shows the whole tax as IGST.
• Read the right panel. You get the base, the GST, the inclusive total, and the CGST/SGST or IGST split, all updated as you type.

Current GST Rates and What Changed

Until September 2025, GST in India ran on five slabs (0%, 5%, 12%, 18% and 28%), with a cess on top for certain luxury and sin goods. The 56th GST Council meeting changed all of that.

Things got much simpler on 22 September 2025. Two slabs now do most of the work, 5% and 18%. A third slab of 40% exists, but only for luxury and sin goods. The 12% slab? Gone. Its items were split between 5% and 18%. The old 28% slab is effectively finished too: nearly everything in it moved to 18%, and only a few items climbed to 40%.

A few special rates stay as they were. Gold and silver jewellery is taxed at 3%, while rough diamonds and some unpolished precious stones sit at 0.25%. Most essentials are at 0%, and so are a few specific categories. Individual health and life insurance, for instance, is now fully exempt. One thing to watch: tobacco and pan masala stay at their old rate plus cess for now, and only shift to 40% later.

So if you deal in a niche category, don't rely on a rate from memory. Check your HSN code against the latest GST guide first.

CGST, SGST and IGST: Why the Split Matters

GST is a single tax for the buyer, but for compliance purposes it is split between the Centre and the state. Which way it splits depends on whether the buyer and seller are in the same state.

• Intra-state sale (buyer and seller in the same state). The total GST is divided equally into CGST (Central GST) and SGST (State GST). On an 18% sale, that is 9% CGST and 9% SGST. The invoice has to show both lines separately.
• Inter-state sale (buyer in a different state from the seller). A single IGST is charged at the full rate. The Centre collects it and later transfers the state's share to the destination state. The buyer is not affected, but the invoice needs to show IGST, not CGST and SGST.

This is also why getting the place of supply right matters. If a Delhi seller treats a sale to a Karnataka buyer as intra-state and charges CGST + SGST, the Karnataka buyer cannot claim input tax credit and the seller has to reissue the invoice with IGST instead. The total tax is the same. The classification is not.

Quick Notes for Business Users

Two more things are worth keeping in mind if your business is registered under GST.

First, the calculator works on the standard GST rates, but not every small business pays those. If you're on the composition scheme, you pay a flat rate on your total turnover instead: 1% for traders and manufacturers, 5% for restaurants, and 6% for most other service providers. The catch is that you can't claim input tax credit, and you can't charge GST to your customers either.

Second, the GST you hand over isn't simply the GST you collect on sales. The tax you've already paid on your purchases (input tax) is set off against the tax you charge on sales (output tax), and you deposit only the difference with the government, not the full output amount. That's why the calculator shows you the GST on a single transaction, not what you'll actually owe at the end of the month.

For the bigger picture, see our guides on GST returns, MSME registration for small businesses, and cess for the additional levies that sit alongside GST on certain goods.

Where GST Sits in the Wider Tax Picture

GST is an indirect tax. It applies to transactions, not to what you earn, which puts it in a different bucket from the direct taxes on your income. If you also handle salary and payroll, the Income Tax Calculator works out personal tax under the current slabs, and our TDS guide covers the tax employers deduct from salary before it's paid out. For a business running its own back office, TankhaPay's payroll software handles statutory deductions like professional tax along with the rest of the compliance work.