GST Calculator
Add or remove GST at any rate with CGST/SGST split.
Base amount
₹10,000.00
GST amount (18%)
₹1,800.00
CGST ₹900.00 + SGST ₹900.00
Total amount
₹11,800.00
Formula used: GST amount = Base × Rate ÷ 100, Total = Base + GST amount. CGST and SGST are each half of the GST amount for intra-state supply.
What is GST and how is it calculated?
Goods and Services Tax (GST) is India's indirect tax on the supply of goods and services, charged at slab rates of 5%, 12%, 18% or 28% depending on the item. There are two directions you'll need:
Adding GST to a base (exclusive) price: GST amount = Base × Rate ÷ 100, and Total = Base + GST amount.
Removing GST from an inclusive price (working backwards from an MRP or invoice total): Base amount = Total ÷ (1 + Rate ÷ 100), and GST amount = Total − Base amount.
For supply within the same state, GST is split equally into CGST (Central GST) and SGST (State GST) — each is exactly half of the total GST amount. For inter-state supply, the full amount is charged as IGST instead, which equals CGST + SGST combined.
How to use this GST calculator
- 1Choose "Add GST" if you have a price before tax, or "Remove GST" if your amount already includes tax.
- 2Enter the amount.
- 3Pick a GST slab — 5%, 12%, 18%, 28% — or enter a custom rate.
- 4Read off the base amount, GST amount (with the CGST/SGST split) and total instantly.
Worked example
A shop sells a chair for a base price of ₹10,000 with 18% GST. Adding GST: GST amount = ₹10,000 × 18 ÷ 100 = ₹1,800, split as CGST ₹900 + SGST ₹900. Total payable = ₹10,000 + ₹1,800 = ₹11,800.
Now suppose an invoice shows ₹11,800 as the final, GST-inclusive amount at 18%. Removing GST: Base amount = ₹11,800 ÷ 1.18 = ₹10,000, and GST amount = ₹11,800 − ₹10,000 = ₹1,800 — matching the first example exactly, as expected.
Frequently asked questions
›What are the standard GST slabs in India?
The common slabs are 0%, 5%, 12%, 18% and 28%, with 18% applying to most goods and services. This calculator includes quick buttons for 5%, 12%, 18% and 28%, plus a custom rate field for any other percentage.
›What's the difference between adding and removing GST?
Adding GST starts from a base (exclusive) price and works out the tax and total. Removing GST starts from a final, tax-inclusive price — such as an MRP — and works backwards to find the original base amount and the tax embedded in it. These are not the same as simply taking a percentage of the total.
›Why are CGST and SGST always equal?
For a sale within the same state, the total GST is split 50/50 between the Central and State governments as CGST and SGST. For a sale between two different states, the same total amount is instead charged in full as IGST rather than being split.
›Is my data uploaded anywhere?
No. All the arithmetic runs directly in your browser using JavaScript — nothing is sent to a server, so amounts you enter stay private.
›Can I use this for currencies other than the rupee?
The formulas are currency-agnostic — only the labels and ₹ symbol are India-specific. You can treat the numbers as any currency; just apply your own tax rate instead of a GST slab.