🧾 GST Calculator
Add GST to a price or remove it from a GST-inclusive amount at any slab — with the net, GST and gross amounts and the CGST/SGST split shown instantly. Free and private.
GST, Both Ways
Whether you're pricing a product or checking an invoice, the maths is instant.
Add or Remove
Add GST to a base price, or work backwards to remove GST from an inclusive total.
All Slabs
One-tap 3, 5, 12, 18 and 28% rates, plus a custom rate for anything else.
CGST / SGST Split
See the central and state GST split automatically for intra-state billing.
Free & Private
Runs in your browser — no login, no limits, dark mode and responsive.
How to Use the GST Calculator
Four steps — results update the moment you type.
Choose add or remove
Pick whether you're adding GST to a net price or removing it from a gross price.
Enter the amount
Type the price into the box — results update instantly.
Pick the GST rate
Tap a slab (5/12/18/28%) or enter a custom rate.
Read the breakdown
See the net, GST and gross amounts plus the CGST/SGST split.
Frequently Asked Questions
Adding and removing GST, CGST/SGST, slabs and the GST formula.
How do I calculate GST on an amount?
To add GST, multiply the net amount by the GST rate and add it. For example, 18% GST on ₹1,000 is ₹180, making the total ₹1,180. Enter the amount and pick a rate above and the calculator does this instantly.
How do I remove GST from an inclusive price?
Use the reverse formula: net = gross × 100 ÷ (100 + rate). For a ₹1,180 price that includes 18% GST, the net is 1,180 × 100 ÷ 118 = ₹1,000, so the GST portion is ₹180. Switch to 'Remove GST' mode to do this automatically.
What are CGST and SGST?
For sales within a state, GST is split equally into CGST (Central GST) and SGST (State GST). So 18% GST is 9% CGST + 9% SGST. For inter-state sales it's charged as a single IGST at the full rate. The calculator shows the CGST/SGST split for you.
What are the GST slabs in India?
The main GST rates are 5%, 12%, 18% and 28%, with 3% used for items like gold and 0% for many essentials. The 18% slab is the most common for services. You can also enter a custom rate.
What is the GST formula?
GST amount = net amount × rate ÷ 100. Gross (inclusive) = net + GST. To go backwards: net = gross × 100 ÷ (100 + rate). The calculator applies whichever formula matches your selected mode.
Is this GST calculator free?
Yes. It's completely free, needs no sign-up, and runs entirely in your browser, so your figures stay private and results are instant.