Formula
GST = price × rate ÷ 100; price with GST = price + GSTprice without GST = GST-inclusive price × 100 ÷ (100 + rate)
- For a same-state sale the GST is split equally into CGST and SGST (or UTGST); for an inter-state sale it is charged as IGST.
To add GST, multiply by the rate. To remove it, divide by 1 plus the rate.
Worked example
18% GST on 1,000
- The amount you entered
- Excludes GST — add GST to it
- Amount
- 1,000
- GST rate
- 18 %
- Currency symbol
- ₹ Rupee (INR)
Price including GST
₹1,180.00
GST amount: ₹180.00
Price without GST: ₹1,000.00
CGST (half, same-state sale): ₹90.00
How it works
At 18%, 1,000 becomes 1,180: the GST is 180, split into 90 CGST and 90 SGST for a sale within a state. To remove GST from a price, divide by 1.18 — not by taking 18% off. A GST-inclusive 1,000 is 847.46 before tax and 152.54 is GST, because the tax is 18% of the smaller pre-tax price.
From 22 September 2025 most goods and services moved to two main slabs, 5% and 18%, with a 40% rate for a short list of luxury and sin goods; the 12% and 28% slabs were removed, and special rates such as 0.25% and 3% remain for items like rough diamonds and gold. Which rate applies to a product or service depends on its classification, so confirm it before invoicing. Enter any rate you need — the tool does the arithmetic and doesn't decide the rate.
For discounts before tax use the Discount Calculator; for profit on a sale see Profit and Loss Calculator; the arithmetic is the same as a percentage increase.
Assumptions and limits
- You choose the rate; the tool does not look up the rate for a product.
- Cess, TCS and state-specific levies aren't included.
Rules, sources and review date
- Applies to
- GST rate structure in force from the GST Council's 56th meeting (5%, 18% and 40% main slabs) — India
- Effective from
- 22 Sep 2025
- Last checked
- 3 Oct 2026
- Sources
- Note
- The arithmetic is rate-independent; the dates and slab description above are only the context for the suggested rates.