GST Calculator India
Goods and Services Tax is charged on almost every sale in India, and you often need to move between the price before GST and the price including it — for invoices, quotes, purchases and filing returns. This calculator adds or removes GST at any rate and splits the tax the way the law does: equal halves of CGST (Centre) and SGST or UTGST (State/Union Territory) for a sale within a state, or the whole amount as IGST for a sale between states. Since 22 September 2025 the main slabs are 5% and 18%, with 40% for sin and luxury goods, plus special low rates; the old 12% and 28% rates are included only for checking older invoices.
How to use the gst calculator india
- Choose whether to add GST to a price or remove it from a total.
- Enter the amount and pick the GST rate that applies to your goods or service.
- Choose within-state or inter-state supply to see the right split.
- Check the rate for your HSN/SAC code on the GST portal before invoicing.
Formula
Adding GST: GST = price × rate; total = price + GST. Removing GST: price = total ÷ (1 + rate); GST = total − price (not total × (1 − rate)). Within a state, CGST = SGST = GST ÷ 2; between states, IGST = GST. At 18%, GST inside a total is 18/118 of it.
Worked examples
Add 18% GST to ₹10,000
GST is ₹1,800.00, the total is ₹11,800.00, split as CGST ₹900.00 and SGST ₹900.00.
Remove 18% GST from ₹11,800 (inter-state)
The price before GST is ₹10,000.00 and IGST is ₹1,800.00.
The 40% slab
On ₹1,000 of goods taxed at 40%, GST is ₹400.00.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- A bill totals ₹23,600 including 18% GST on a local sale. What is the CGST?
Show answer
Price before GST: ₹20,000.00 · Total GST: ₹3,600.00
Common mistakes to avoid
- Subtracting the GST percentage from a tax-inclusive total. Divide by (1 + rate) instead.
- Using an out-of-date rate. Rates changed on 22 September 2025; check the current rate for your item.
- Charging CGST+SGST on an inter-state sale (or IGST on a local one).
- Applying one rate to a mixed invoice. Different items can carry different rates.
- Ignoring cess or special rates on certain goods.
Frequently asked questions
What are the current GST rates in India?
Since 22 September 2025 the main rates are 5% and 18%, with 40% for sin and luxury goods, plus special rates such as 3% on gold and 0.25% on rough diamonds. Many items are nil-rated. Check the GST portal for your item.
How do I calculate GST from a total price?
Divide the total by 1 plus the rate to get the price before GST; the difference is the GST. At 18%, divide by 1.18.
What is the difference between CGST, SGST and IGST?
For sales within a state, GST is split equally into CGST (Centre) and SGST/UTGST (State). For sales between states, the whole amount is IGST.
Why are the old 12% and 28% rates included?
Only so you can check invoices dated before 22 September 2025. Those slabs no longer apply to new supplies.
Is this tax advice?
No. Check rates and treatment on the GST portal or with a professional.
Sources and further reading
By Thomas M, Registered Investment Adviser (South Carolina), who launched his own financial advisory firm in 2010. Last reviewed September 26, 2026. Found a mistake? Tell us; see our editorial policy.