Finance
GST Calculator
Add GST to a price or work out how much GST is already inside an inclusive amount, with the split into CGST and SGST for supply within a state or IGST for supply between states.
How to use this calculator
- Choose whether you are adding GST to a base price or removing it from a total.
- Enter the amount.
- Pick the GST rate, or type one in.
- Choose whether the supply is within a state or between states to see the correct tax split.
Formula
Adding GST: GST = Amount × Rate ÷ 100. Removing GST: Base = Total × 100 ÷ (100 + Rate)
- Amount
- price before tax when adding GST
- Total
- price including tax when removing GST
- Rate
- applicable GST rate in percent
Within a state, CGST and SGST are each half of the total GST. Between states, the whole amount is IGST.
Worked example
A service priced at ₹10,000 before tax, at 18% GST, supplied within the same state.
- GST10,000 × 18 ÷ 100 = ₹1,800
- CGST (9%)₹900
- SGST (9%)₹900
The invoice total is ₹11,800, made up of ₹10,000 plus ₹900 CGST and ₹900 SGST.
CGST, SGST and IGST
GST is one tax collected in two ways. When goods or services move within a state, the total rate is split equally between central GST and state GST. When they move between states, the same total is charged as a single integrated GST that the centre later apportions.
For the buyer the total is identical. The split matters for invoicing and for claiming input tax credit correctly.
Inclusive and exclusive pricing
Retail prices in India are usually GST-inclusive: the tag price is what you pay. Business quotes are often exclusive, with GST added on the invoice. Extracting GST from an inclusive price is not the same as taking the rate off the total, which is the most common mistake in manual calculations.
To remove 18% GST from ₹1,180 you divide by 1.18 to get ₹1,000, not subtract 18% of ₹1,180.
Things to keep in mind
- Rates are set by the GST Council and are revised from time to time. Check the current rate for your HSN or SAC code before relying on an invoice figure.
- Some goods attract a compensation cess in addition to GST, which this calculator does not include.
- Exempt and zero-rated supplies are treated differently from a 0% rate for input tax credit purposes.
Frequently asked questions
How do I remove GST from a total amount?
Divide the total by (100 + rate) and multiply by 100. For 18% GST on a ₹1,180 total, the base price is 1,180 × 100 ÷ 118 = ₹1,000 and the GST is ₹180. Choose the remove GST option above to do this automatically.
When is IGST charged instead of CGST and SGST?
IGST applies when the supplier and the place of supply are in different states or union territories, and on imports. Within a single state, the same total is split into CGST and SGST.
Which GST rate applies to my product?
It depends on the HSN code for goods or the SAC code for services. The GST Council publishes the schedules and revises them periodically, so confirm the current rate for your specific item rather than assuming.
Related articles
- GST basics for a small businessWhat CGST, SGST and IGST mean, how inclusive pricing works, and the arithmetic mistakes that show up most often on invoices.1 min read
- Five percentage mistakes that cost real moneyStacked discounts, percentage points, reversing a rise, and the other percentage errors that show up in shopping, salary and investment decisions.1 min read
Was this calculator useful?
Quick reaction, a note, or both — whatever's useful to you.
Contact details are optional and only used to reply to you — never shared, never used for marketing.