GST Calculator
Add GST to a base price or remove GST from a total amount. Instant CGST and SGST breakdown for all Indian GST slabs. Runs entirely in your browser.
This calculator adds GST to a base price or extracts it from a GST-inclusive price, across the 5%, 12%, 18% and 28% slabs. It splits the tax into CGST and SGST at half the rate each, and returns the net amount, tax amount and gross total.
Calculation Mode
Enter the base price (excl. GST). GST will be added on top.
GST Rate
GST Breakdown
Enter an amount
Results will appear here instantly.
About this tool
A fast, accurate GST calculator built for Indian businesses and consumers. Use Add GST to compute the final price after tax, or Remove GST to find the pre-tax base price hidden inside a GST-inclusive amount. Results update as you type — no submit button needed.
All standard Indian GST slabs are available as one-click presets — 3%, 5%, 12%, 18%, and 28% — plus a Custom option for any rate. The breakdown always shows the total GST amount split into equal CGST and SGST halves for intra-state compliance.
How to use
Choose your mode
Select Add GST to calculate the final price after tax, or Remove GST to extract the base price from a GST-inclusive amount.
Enter the price
Type the base amount (Add GST mode) or the total amount including tax (Remove GST mode). The result updates instantly.
Select the GST rate
Pick a standard Indian GST slab — 3%, 5%, 12%, 18%, or 28% — or enter a custom rate using the Custom option.
Read the results
See the GST amount, CGST and SGST halves for intra-state compliance, and the final or base price — all updated as you type.
A worked example — and the mistake almost everyone makes
Adding GST is the easy direction. On a base price of ₹10,000 at 18%, the tax is ₹1,800 and the invoice total is ₹11,800. For an intra-state supply that ₹1,800 splits into ₹900 CGST and ₹900 SGST — each half the applicable rate.
Removing GST is where bills go wrong. Given a GST-inclusive price of ₹11,800, the instinct is to subtract 18% of it: 11,800 − 2,124 = ₹9,676. That answer is wrong, and it is wrong by ₹324.
The reason is that the 18% was charged on the base price, not on the total. So you have to divide rather than subtract: base = gross ÷ (1 + rate ÷ 100), which gives 11,800 ÷ 1.18 = ₹10,000 exactly. The tax component is the remaining ₹1,800.
The error grows with the rate. At 28% the subtract-method is off by nearly 8% of the base value — enough to matter on a single invoice, and enough to distort a whole quarter's books if it becomes habit. Use the “remove GST” mode above rather than doing it in your head.
At a glance
- Slabs supported
- 5%, 12%, 18% and 28%
- Directions
- Add GST to a base price, or extract GST from a GST-inclusive price
- Tax split
- Splits the total into CGST and SGST, each half the applicable rate
- Outputs
- Net amount, tax amount and gross total
- Reverse calculation
- Base = gross ÷ (1 + rate ÷ 100) — the step most often done wrong by hand
- Privacy
- Calculated locally; nothing is transmitted
Sources & references
- GST Portal, Government of India — Official GST rates, returns and registration
- CBIC — Central Board of Indirect Taxes and Customs — Rate notifications and the HSN classification that decides which slab applies
Related tools
Frequently asked questions
Common questions about GST calculation and Indian tax slabs.
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