GST Calculator

GST (Goods and Services Tax) is the single indirect tax charged on most goods and services sold in India. It replaced a stack of older taxes — VAT, service tax, excise duty and several others — in July 2017. The seller adds GST to the price, collects it from the buyer and pays it to the government, so the tax is really paid by the final customer. A registered business can claim back the GST it paid on its own purchases (input tax credit), which means the tax only lands once on the value each business actually adds.

Since 22 September 2025 there are two main rates plus one special rate: a merit rate of 5%, a standard rate of 18%, and a special de-merit rate of 40% for a short list of luxury and harmful items. Many essentials are Nil-rated (no GST at all). This structure came from the 56th GST Council meeting on 3 September 2025, which folded the old four-slab system — 5%, 12%, 18% and 28% — into it: most 12% items moved down to 5% and most 28% items moved down to 18%. The rate on any specific product is set item by item, so check yours on the CBIC rate finder before you invoice.

Divide, do not subtract. The formula is base = total ÷ (1 + rate ÷ 100). A price of ₹1,180 that includes 18% GST has a base of ₹1,180 ÷ 1.18 = ₹1,000, and the GST inside it is ₹180. Taking 18% off the ₹1,180 instead gives ₹967.60, which is wrong by ₹32.40 — because the 18% was calculated on the smaller base price, not on the bigger inclusive price. Switch this calculator to "Remove GST" and it does the division for you.

They are three names for the same money, split differently depending on where the buyer is. If the seller and the buyer are in the same state, the tax is split in half: CGST goes to the central government and SGST goes to the state government. If they are in different states, the whole amount is charged as one IGST line instead, and the centre later passes the state's share on. The total the buyer pays is identical either way — ₹10,000 at 18% costs ₹11,800 whether it is billed as CGST ₹900 plus SGST ₹900 or as IGST ₹1,800.

After the discount, as long as the discount is shown on the invoice at the time of sale. GST is charged on the transaction value — the amount the buyer actually pays — so a ₹1,000 item sold with a ₹200 discount is taxed on ₹800, not ₹1,000. A discount agreed after the sale is treated differently and usually needs a credit note before the tax can be reduced. If you are working out a sale price, use the discount calculator first and bring the discounted figure into this one.

The composition scheme is a simplified option for small businesses. Instead of charging GST on each sale and filing detailed returns, a composition dealer pays a small flat percentage of total turnover to the government out of its own pocket. Because the tax is never collected from the customer, a composition dealer cannot show GST as a separate line and issues a "bill of supply" rather than a tax invoice — and the customer cannot claim input tax credit on it. The flat percentage depends on the type of business, and the eligibility limits change from time to time, so confirm the current terms on the GST portal before opting in.

Rounding. GST works out to paise on almost every real invoice, and the tax amount on an invoice is normally rounded to the nearest rupee. Software also differs in where it rounds: some round the CGST and SGST halves separately and then add them, others round only the final total. Both are defensible and they can disagree by up to a rupee. This calculator shows the unrounded figure so you can see exactly where the difference comes from.

No. Everything runs on your own device, inside the page you are reading. The amounts and rates you type are never uploaded, stored or logged, and once the page has loaded you can keep using it with no internet connection.