What is GST Calculator?
Calculate GST amount, add or remove GST from any price with complete CGST, SGST and IGST breakdown Simply enter your values, and the calculator instantly computes accurate results using standard financial formulas. All calculations are performed entirely in your browser — nothing is stored or transmitted.
Reviewed and last updated on 30 July 2026 by the FinCalc Pro Editorial Team.
GST Exclusive vs GST Inclusive — Two Different Calculations
The GST Calculator handles both pricing conventions because the arithmetic is not the same. Adding GST to a base price means multiplying: a ₹10,000 base at 18% gives ₹1,800 of tax and a ₹11,800 final price. Removing GST from an inclusive price means dividing: if the selling price is ₹11,800 inclusive, the base is ₹11,800 ÷ 1.18 = ₹10,000, and the embedded tax is ₹1,800.
Retailers who price goods "inclusive of GST" often make the mistake of computing 18% of the selling price and calling that the tax. That is wrong — the tax is 18% of the pre-tax base. An item sold at ₹118 inclusive carries ₹18 of GST, not ₹21.24. Using the calculator in "remove GST" mode gives the correct base and tax every time.
CGST, SGST and IGST: When Each Applies
GST is a destination-based tax split between the centre and the states. On an intra-state sale — both seller and buyer in the same state — the total rate is split equally into CGST and SGST. An 18% intra-state invoice shows 9% CGST and 9% SGST. On an inter-state sale, the full 18% is charged as IGST, and the centre passes the state portion to the destination state.
The calculator displays the CGST/SGST split for intra-state and a single IGST figure for inter-state, so the same base amount works for either case. Business owners filing GSTR-1 need exactly this split on every invoice to claim matching input tax credit.
Using the Calculator for Invoicing and Bookkeeping
For invoicing, run the base price through "add GST" to produce the gross invoice value and the tax line. For bookkeeping, run the gross receipt through "remove GST" to recover the taxable value and the tax collected. Reversing one with the other should always bring you back to the starting number — a quick cross-check that catches entry errors.
Remember that the GST you charge on sales is not your profit; it is collected on behalf of the government and offset against the input tax credit you claim on purchases before the net amount is paid in GSTR-3B. Small businesses under the composition scheme skip input credit entirely and pay a flat rate instead — the GST Composition Calculator covers that separate path.
Formula Used
For exclusive GST (adding to price): GST = Amount × Rate/100 | For inclusive GST (removing from price): Original = Amount / (1 + Rate/100)
How to Use This Calculator
- Enter the base amount or GST-inclusive amount
- Select GST rate (5%, 12%, 18%, or 28%)
- Choose whether to add GST or remove GST from the amount
- Click Calculate to see CGST, SGST (or IGST for interstate)
- Copy the breakdown for your invoice or accounting
Worked Example
Base Price: ₹10,000 | GST Rate: 18% → CGST: ₹900 | SGST: ₹900 | Total GST: ₹1,800 | Final Price: ₹11,800
Why Use This Tool?
- Instantly calculate GST for invoicing
- Get CGST/SGST split for intrastate transactions
- Get IGST amount for interstate transactions
- Works for all GST slabs: 5%, 12%, 18%, 28%
Frequently Asked Questions
What are the GST rates in India?
GST rates in India are: 0% (essential items like food grains), 5% (basic necessities), 12% (processed foods, electronics), 18% (most goods and services), 28% (luxury goods, automobiles, tobacco).
What is CGST and SGST?
For intrastate transactions, GST is split equally into CGST (Central GST) and SGST (State GST). For interstate transactions, IGST (Integrated GST) = CGST + SGST is charged.
How to calculate GST on an amount?
To add GST: Final Price = Base Price × (1 + GST Rate/100). To find GST amount: GST = Base Price × GST Rate/100. Example: ₹1,000 + 18% GST = ₹1,180. GST amount = ₹180.
Explore more tax (india) calculators or try our other free financial tools.