GST calculator
Add GST to a price or remove GST from an inclusive amount at any rate. Get the net amount, tax and the CGST + SGST or IGST split in one click.
- Runs in your browser – private
- Instant results
- Free forever, no sign-up
How to use the GST Calculator
- 1
Choose Add GST (amount is before tax) or Remove GST (amount already includes tax).
- 2
Enter the amount and pick the GST rate – or type a custom rate.
- 3
Select same-state or inter-state supply to see the CGST/SGST or IGST breakup.
How to calculate GST (with formulas)
Our GST calculator online uses the same formulas as your accountant:
Remove GST: Net = Amount ÷ (1 + Rate ÷ 100) · GST = Amount − Net
Example: ₹10,000 + 18% GST = ₹1,800 tax, ₹11,800 total. To remove GST from ₹11,800 at 18%: 11,800 ÷ 1.18 = ₹10,000 net and ₹1,800 GST. This is why it is also called a reverse GST calculator or GST inclusive calculator.
CGST, SGST and IGST explained
- Intra-state supply (seller and buyer in the same state): GST is split equally into CGST (central) and SGST/UTGST (state). 18% GST = 9% CGST + 9% SGST.
- Inter-state supply (different states, or most e-commerce shipments across states): the full rate is charged as IGST.
Switch between the two options to get the exact breakup for your tax invoice. Need a printable invoice? Use our free GST invoice generator.
GST rates in India
Following the GST rate rationalisation that took effect on 22 September 2025, most goods and services fall under two main slabs – 5% and 18% – with a 40% rate for select luxury and sin goods, plus special rates such as 0%, 0.25% and 3% for specific items. The older 12% and 28% slabs are kept in the dropdown for checking older invoices.
Rates are set per HSN/SAC code and can change, so always confirm the current rate for your product on the official GST portal or with your tax adviser.
Frequently asked questions
How do I remove GST from a total amount?
Divide the total by (1 + GST rate/100). For ₹1,180 at 18%: 1,180 ÷ 1.18 = ₹1,000 net, so GST is ₹180. Choose “Remove GST” and the calculator does this automatically.
How is 18% GST calculated?
Multiply the net amount by 0.18. On ₹5,000 that is ₹900 GST and a ₹5,900 total. Within a state it is shown as 9% CGST (₹450) + 9% SGST (₹450).
When do I charge IGST instead of CGST and SGST?
Charge IGST when the place of supply is in a different state from your registered business location. Charge CGST + SGST when both are in the same state.
What are the current GST slabs?
After the September 2025 reform, the main slabs are 5% and 18%, with 40% for select luxury and sin goods and special rates like 0%, 0.25% and 3%. Check the rate for your HSN code before invoicing.
Can I use this GST calculator for services?
Yes. The maths is the same for goods and services – just pick the rate that applies to your SAC code.
Is this GST calculator free?
Yes, it is completely free with no sign-up, and nothing you type leaves your browser.