Free tool
Calculate taxable value, GST and invoice total for common India GST rates, including intra-state and inter-state supplies.
GST workspace
Choose the transaction facts you have already verified. The tool performs arithmetic; it does not determine the legal rate or place of supply.
This GST calculator separates the taxable value and GST for an amount that is either inclusive or exclusive of tax. Choose an intra-state supply to split GST equally into CGST and SGST, or an inter-state supply to show IGST. Confirm the applicable rate, place of supply and tax treatment with current official guidance.
How to use it
Enter the amount and choose the GST rate that applies to the supply.
Choose whether the amount already includes GST.
Select intra-state or inter-state supply to calculate CGST and SGST or IGST.
Apply the result within a current GST invoicing process.
Lay out the required fields with the GST invoice format.
Confirm why product classification matters in the HSN code guide.
Browse the complete set of free invoicing tools.
For what GST is and how CGST, SGST and IGST fit together, read what is GST.
GST calculation formula
This online GST calculator for India does the arithmetic for you. These are the formulas behind it, so you can check a figure on paper or in a spreadsheet. The amounts are illustrative examples at 18%, not a statement of which rate applies to your supply.
Multiply the taxable value by the GST rate and divide by 100. Add the result to the taxable value to reach the invoice total. For example, a taxable value of ₹10,000 at 18% carries GST of ₹1,800, so the total is ₹11,800.
When a price already includes GST, extract the tax instead of adding it. Multiply the GST-inclusive price by the rate and divide by 100 plus the rate. For example, an inclusive price of ₹11,800 at 18% contains ₹1,800 of GST on a taxable value of ₹10,000. In the calculator, choose Includes GST to run this reverse calculation.
For an intra-state supply, the GST amount is divided equally between CGST and SGST. For an inter-state supply, the whole amount is IGST. In the example, ₹1,800 of GST is ₹900 CGST plus ₹900 SGST within a state, or ₹1,800 IGST between states. The place-of-supply rules decide which split applies.
Use the result well
Use CGST and SGST for an intra-state supply and IGST for an inter-state supply, subject to the applicable place-of-supply rules.
The calculator provides common selectable rates, but the correct rate follows the goods or service classification and current official notification - not the number most often used.
For a tax-inclusive amount, the GST component is extracted from the total. For a tax-exclusive amount, GST is added to the taxable value.
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Common questions
For an intra-state supply, the calculator divides the selected total GST rate equally between CGST and SGST. An 18% rate therefore appears as 9% CGST and 9% SGST. This arithmetic does not determine whether a supply is intra-state; confirm the supplier location and place-of-supply treatment before relying on the split.
IGST generally applies when the supply is treated as inter-state under the applicable place-of-supply rules. Select the inter-state option only after checking the supplier location, recipient or destination details and the nature of the supply. The calculator shows the arithmetic once that classification is chosen; it does not make the legal classification for you.
An exclusive amount is the taxable value before GST, so the selected tax is added to reach the invoice total. An inclusive amount already contains GST, so the calculator works backward to separate the taxable value and tax component. Check which convention the quoted or contracted amount uses before preparing the invoice.
To add GST, multiply the taxable value by the rate and divide by 100. At 18%, ₹10,000 × 18 ÷ 100 gives ₹1,800 of GST and a total of ₹11,800. To reverse it from a GST-inclusive price, multiply the price by the rate and divide by 100 plus the rate: ₹11,800 × 18 ÷ 118 gives ₹1,800. These figures are illustrative; confirm the rate that applies to the supply.
Yes. Choose Includes GST and enter the GST-inclusive amount. The calculator divides the amount by one plus the rate to find the taxable value, and the difference is the GST, shown as CGST and SGST for an intra-state supply or as IGST for an inter-state supply. Use it when a quoted or contracted price already contains tax.
Select the rate supported by the current classification and notification for the actual goods or services. Common rates include 5%, 12%, 18% and 28%, but nil, exempt and other rates also exist. Verify the HSN or service classification and current CBIC rate schedule instead of assuming that a commonly used rate applies.
Use the calculation as an arithmetic check, then confirm the GSTINs, invoice type, place of supply, HSN or service classification, applicable rate, required fields and rounding treatment. A compliant invoice depends on the complete transaction record, not the tax amount alone. Keep the official rate source and business review with the final invoice.
