What is GST, and who needs a GST calculator?
GST (Goods and Services Tax) is the indirect tax charged on most goods and services in India. This calculator does two jobs. It adds GST to a price that does not include tax, and it removes GST from a price that already includes it. In both cases it shows the base amount, the GST amount and the total.
Shopkeepers, freelancers, small business owners and accountants use it while preparing invoices. Ordinary buyers use it to check that a bill is correct, or to find the price before tax from a figure that already includes GST.
Which GST rates apply now?
Since 22 September 2025, most goods and services fall under 5%, 18% or 40%, with 0% for exempt essentials. The older 12% and 28% slabs were largely removed. Use the rate buttons for a quick start, or type any rate into the box, and always confirm the rate for your specific item or service in the official notification.
Formula used
- Add GST: GST = Amount × Rate ÷ 100, and Total = Amount + GST
- Remove GST: Base = Total ÷ (1 + Rate ÷ 100), and GST = Total − Base
- Within one state: CGST = SGST = GST ÷ 2
Worked example
Adding GST: a service costs ₹10,000 before tax and attracts 18% GST. GST = 10,000 × 18 ÷ 100 = ₹1,800, so the total is ₹11,800. Within one state, that is ₹900 CGST and ₹900 SGST.
Removing GST: a garment is sold at ₹5,250 including 5% GST. Base = 5,250 ÷ 1.05 = ₹5,000, and GST = 5,250 − 5,000 = ₹250. Switch to Remove GST, enter 5,250 and pick 5% to see the same result.
Frequently asked questions
What are the current GST rates in India?
Since 22 September 2025, most goods and services are taxed at 5%, 18% or 40%, with 0% for exempt essentials. The old 12% and 28% slabs were largely removed. Some items have special rates, so check the official notification for your product.
How do I take GST out of a price that already includes it?
Divide the total by 1 plus the rate. Do not simply subtract the percentage. For ₹11,800 at 18%, the base is ₹10,000, whereas subtracting 18% of 11,800 would wrongly give ₹9,676.
What is the CGST and SGST split?
For a sale within one state, GST is shared equally between the Centre (CGST) and the State (SGST). For a sale between states, the full amount is charged as IGST. The calculator shows total GST, so halve it for the CGST and SGST split.
Why does the tool still show 3%, 12% and 28% buttons?
They are quick shortcuts for older invoices and special cases. You can also type any rate in the box. Always confirm the correct current rate for your item before billing.
Can I use these results on a GST invoice?
Use them as a guide. A valid invoice needs the correct HSN or SAC code and rate, and rounding rules can differ slightly. Confirm with your accountant before filing returns.
Limitations and accuracy
The calculator applies a single rate to a single amount. It does not handle cess, TCS, reverse charge, the composition scheme or input tax credit, and it does not know which rate your product falls under. Rates change through GST Council decisions, so verify them with an official source or a tax professional. This tool is for information only and is not tax advice.