GST Calculator India
Add GST to a price or work backwards out of a quoted one, with the tax split the way an invoice shows it.
GST Calculator
GST
₹180.00
- Amount before GST₹1,000.00
- Amount after GST₹1,180.00
- CGST₹90.00
- SGST₹90.00
- IGST₹0.00
Works out in your browser. Nothing you type is sent anywhere.
In short: GST Calculator
On ₹1,000 at 18%, the GST is ₹180.00, which makes the amount before tax ₹1,000.00 and after tax ₹1,180.00. Within a state that splits into ₹90.00 of CGST and ₹90.00 of SGST; between states the whole amount is charged as IGST instead.
What is GST?
Goods and Services Tax is an indirect tax charged on a supply, split into central and state halves within a state and charged as a single integrated tax between states.
How is GST calculated?
To add GST, multiply the amount by the rate and divide by a hundred. To take GST out of a price that already includes it, divide the price by one plus the rate over a hundred, and the difference is the tax.
- GSTthe tax amount
- Athe amount GST applies to
- rthe rate, as a percentage
A worked example
| Amount | ₹1,000 |
|---|---|
| GST rate (%) | 18% |
| The amount above is | Before GST (add GST) |
| Supply | Within the state (CGST + SGST) |
| Result | |
| GST | ₹180.00 |
| Amount before GST | ₹1,000.00 |
| Amount after GST | ₹1,180.00 |
| CGST | ₹90.00 |
| SGST | ₹90.00 |
| IGST | ₹0.00 |
Every figure in this table is produced by the same calculation the tool above runs.
How to use this GST calculator
- Enter the amount from the invoice or the quotation.
- Pick the rate that applies to that good or service.
- Say whether the amount already includes GST or not.
- Choose whether the supply is within a state or between two.
Questions people ask
How do I remove GST from a price?
Divide the inclusive price by one plus the rate expressed as a decimal, which gives the amount before tax. The difference between the two is the GST. Setting the mode above to the inclusive option does this for you.
What is the difference between CGST, SGST and IGST?
A supply within a state is split equally between the centre and the state, as CGST and SGST. A supply between states is charged as a single integrated tax, IGST, which the centre later apportions. The total rate is the same either way.
Which rate applies to my product?
The rate depends on the classification of the good or service in the CBIC schedules, and some items also attract a cess. This tool does the arithmetic for a rate you choose; it does not decide the rate for you. Check the schedule in the sources below or ask your accountant.
Is GST charged on the discounted price or the full one?
On the price after any discount shown on the invoice, provided the discount was agreed before or at the time of supply. Discounts given later have their own conditions. The discount tool shows the sequence of discount and then GST.
Accuracy and sources
Where the figures come from
- Central Board of Indirect Taxes and Customs: GST rate schedules as of 22 September 2025
Estimate only. Not financial or tax advice.
Checked by the Daytoolz team on 16 October 2026. How we check our tools.
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