GST Calculator

GST Calculator: add or remove Goods and Services Tax in seconds

This GST Calculator helps you work out the Goods and Services Tax on any amount in Indian Rupees. You enter a value, pick a rate of 5%, 12%, 18% or 28%, and choose whether you want to add GST to a base price or remove GST from a price that already includes it. The tool then shows the tax portion, the net (taxable) value and the gross (final) value, and splits the tax into CGST plus SGST or a single IGST figure.

It is built for the people who deal with these numbers every day: small business owners and shopkeepers preparing tax invoices, freelancers and consultants quoting fees, accountants and GST practitioners cross-checking entries, students learning indirect tax, and ordinary buyers who simply want to know how much of a bill is tax.

The exact formula, in words

To add GST (exclusive to inclusive): the GST amount equals the base price multiplied by the rate divided by 100. The final price equals the base price plus that GST amount. In short, Final = Base multiplied by (1 + rate/100).

To remove GST (inclusive to exclusive): the base price equals the inclusive price divided by (1 + rate/100). The GST amount is then the inclusive price minus that base price. Never simply take a flat percentage off an inclusive price, because that gives the wrong answer.

Splitting the tax: for a supply within the same state or union territory, the tax is shared equally as CGST and SGST, each being half the rate. For a supply between two different states, the whole tax is charged as a single IGST at the full rate.

A fully worked example

Suppose a Delhi trader sells goods with a base price of Rs. 10,000 at the 18% slab to a buyer within Delhi.

• GST amount = 10,000 multiplied by 18/100 = Rs. 1,800
• Final invoice value = 10,000 + 1,800 = Rs. 11,800
• Because it is an intra-state supply, the tax splits as CGST 9% = Rs. 900 and SGST 9% = Rs. 900

Now reverse the situation. The buyer sees a shelf price of Rs. 11,800 inclusive of 18% GST and wants the tax portion. Base price = 11,800 divided by 1.18 = Rs. 10,000. GST = 11,800 minus 10,000 = Rs. 1,800. Notice that taking a flat 18% of 11,800 would wrongly give Rs. 2,124, which is why the reverse formula matters.

Had the same sale been made from Delhi to a buyer in Maharashtra, the Rs. 1,800 would appear as a single IGST line of 18% rather than CGST plus SGST.

Current slabs after the September 2025 reform

GST rates are volatile, so always confirm the live rate for your item. Under the GST 2.0 rationalisation effective 22 September 2025, the earlier structure of 0%, 5%, 12%, 18% and 28% was simplified to two main slabs of 5% and 18%, alongside a nil (0%) rate for many essentials and a special 40% de-merit slab for luxury and sin goods such as pan masala, tobacco, aerated drinks and high-end vehicles.

• Most items from the old 12% slab moved down to 5%, and most items from the old 28% slab moved down to 18%.
• The 12% and 28% slabs are largely retired for new supplies, but this calculator still offers them so you can check invoices dated before 22 September 2025 or any residual notified rates.
• Special fixed rates continue outside the main slabs, for example 3% on gold and 0.25% on rough diamonds.
• A compensation cess historically applied above 28% on some goods; under GST 2.0 this has largely been subsumed into the 40% rate, with limited transitional continuation on tobacco products.

Rules and edge cases to keep in mind

• Intra-state vs inter-state is decided by the place of supply, not by where you happen to be sitting. CGST plus SGST applies within one state; IGST applies across states and for most imports.
• Certain goods and services are exempt or nil-rated (many fresh foods, some healthcare and education), so no GST applies at all.
• GST is charged on the transaction value, which usually includes freight, packing and incidental charges unless shown separately as agreed.

Tax treatment and input tax credit

For a GST-registered business, the GST you collect on sales is output tax and the GST you pay on purchases is input tax. You deposit only the difference with the government after claiming input tax credit, so GST is meant to be a pass-through cost, not a business expense. A final consumer, who cannot claim credit, ultimately bears the tax. Registration is generally required once turnover crosses the prescribed threshold (broadly Rs. 40 lakh for goods and Rs. 20 lakh for services, with lower limits of Rs. 20 lakh and Rs. 10 lakh for special-category states), and the exact limits should be confirmed for your case as of FY 2025-26.

Common mistakes and tips

• Do not subtract a flat percentage to strip GST from an inclusive price. Always divide by (1 + rate/100).
• Round the CGST and SGST halves carefully so that together they equal the total GST; rounding each separately can leave a one-paisa mismatch.
• Do not mix IGST with CGST plus SGST on the same invoice line, and confirm the place of supply before choosing.
• Check whether your quoted price is meant to be inclusive or exclusive of GST before you calculate, and state it clearly on quotations.
• Verify the correct slab for your specific HSN or SAC code, since rates changed on 22 September 2025 and a wrong rate can lead to short payment and interest.