GST Calculator India
Calculate the GST amount and total payable on any base price by selecting the applicable GST rate slab, with a CGST/SGST or IGST split for domestic and interstate supplies.
- 1Enter the base price of the goods or service (before tax)
- 2Select the applicable GST rate slab
- 3Choose whether the transaction is intra-state (CGST+SGST) or inter-state (IGST)
- 4Click Calculate to see the tax amount and total payable
What this GST calculator does
Enter a base amount (the price before tax) and a GST rate, and the calculator returns the GST amount, the total payable, and the split into CGST and SGST. For example, a base price of ₹10,000 at 18% gives GST of ₹1,800, a total of ₹11,800, and CGST and SGST of ₹900 each. The rate field accepts any percentage, so it keeps working if rates change.
How GST is structured in India
- CGST + SGST apply when the supplier and the buyer are in the same state. The tax rate is split equally between the Centre (CGST) and the State (SGST). This is the split the tool displays.
- IGST applies to inter-state supplies and to imports, and is charged at the full combined rate. If you are selling to another state, the CGST and SGST split shown here does not apply; the whole GST amount is IGST.
- Rates differ by item. GST rates are set by the GST Council per category of goods and services and have been revised over time. Always confirm the rate for your product or service against the latest official notification or HSN/SAC schedule before invoicing.
Adding GST to a price (exclusive to inclusive)
This is what the calculator performs: GST = base × rate / 100 and total = base + GST. Use it when you quote a price before tax and need to show the customer's final amount.
Removing GST from a price (inclusive to exclusive)
The tool does not do this directly, but the arithmetic is simple. If the shelf price already includes GST, the base price is total × 100 / (100 + rate). For a total of ₹11,800 at 18%, the base is 11,800 × 100 / 118 = ₹10,000, and the GST contained in it is ₹1,800. Enter the resulting base amount in the calculator to see the CGST/SGST split.
Common mistakes
- Calculating GST on the GST-inclusive price. Taking 18% of ₹11,800 gives the wrong tax. Extract the base first, as shown above.
- Applying the wrong rate to a bundle. Different line items on one invoice can carry different rates; calculate each separately.
- Ignoring discounts. GST is generally charged on the transaction value after eligible trade discounts shown on the invoice, so apply the discount first.
- Using the same split for inter-state sales. As noted above, inter-state sales are charged as IGST.
Who uses it
Small shop owners, freelancers and service providers use it to quote prices, check supplier invoices and reconcile figures before filing returns. Shoppers can use the reverse formula to see how much of a price is tax. To produce a complete bill, pair it with the invoice generator, and to estimate profitability after tax use the profit margin calculator.
This calculator is a convenience tool and not tax advice. Rates, exemptions, input tax credit and filing rules are determined by law, so consult the official GST portal or a qualified tax professional for compliance decisions.