Adding GST
Start with the taxable value. Multiply it by the verified rate to obtain GST, then add the two amounts. For an intra-state treatment, the tool displays equal CGST and SGST or UTGST halves.
Invoice arithmetic only
Add or extract GST from a verified rate
Enter an amount, choose whether GST is outside or inside it, then choose the supply treatment you have already verified.
This tool does not decide: HSN or SAC, rate, exemption, place of supply, reverse charge, composition eligibility or input-tax credit.
GST arithmeticNo invoice data saved
On this page
User-verified 18% rate
₹1,180
Invoice value after adding GST to ₹1,000.
- Taxable value
- ₹1,000
- Total GST
- ₹180
- CGST
- ₹90
- SGST / UTGST
- ₹90
- IGST
- ₹0
Formula
Exclusive GST = taxable value × rate. Inclusive taxable value = gross amount ÷ (1 + rate).
Extracting included GST
Do not multiply a tax-inclusive total by the rate. Divide the total by one plus the decimal rate to recover the taxable value; the difference is GST.
Rate verification
Search the responsible CBIC schedule and applicable notification using the actual goods or services classification. A familiar product name alone may not establish the correct rate.
Supply treatment
Intra-state versus inter-state treatment follows place-of-supply rules and the actual parties. This calculator records your verified choice but does not determine it.
Common questions
Questions people ask before using this page
How do I remove GST from a tax-inclusive total?
Divide the tax-inclusive total by one plus the GST rate expressed as a decimal. The difference between the total and the pre-tax amount is the GST component.
Does the calculator select the correct GST rate?
No. Select a rate only after checking the product or service classification and the applicable official rate.
When is GST split into CGST and SGST?
The calculator splits an entered GST amount equally for an intra-state supply. An inter-state supply is shown as IGST. Place-of-supply treatment must be verified separately.