Loans, investing & tax
GST Calculation Examples: Add, Remove, CGST/SGST/IGST
Updated 25 September 2026 · 4 min read
GST is calculated on the taxable value of a supply. Since 22 September 2025 most goods and services fall in two main slabs, 5% and 18%, with 40% for a small list of luxury and “sin” goods. Here are the three calculations you'll need.
1. Adding GST to a price
GST = price × rate ÷ 100 · Total = price + GST
₹10,000 at 18%: GST = ₹1,800, total = ₹11,800.
₹2,000 at 5%: GST = ₹100, total = ₹2,100.
2. Removing GST from an inclusive price
Price before GST = inclusive price × 100 ÷ (100 + rate)
A bill of ₹11,800 including 18% GST: 11,800 × 100 ÷ 118 = ₹10,000, so the GST is ₹1,800.
A common mistake is taking 18% of ₹11,800 (₹2,124) — that overstates the tax.
3. CGST + SGST or IGST?
| Supply | Tax charged on ₹10,000 at 18% |
|---|---|
| Within the same state (e.g. Pune → Mumbai) | CGST 9% ₹900 + SGST 9% ₹900 |
| To another state (e.g. Pune → Bengaluru) | IGST 18% ₹1,800 |
The total is the same — only which government receives it changes. The first two digits of the buyer's GSTIN tell you their state.
Add or remove GST in one clickAdd or remove GST from any amount with CGST, SGST and IGST breakdown.Billing a customer? The GST invoice generator applies CGST/SGST or IGST automatically from the place of supply — see how to create a GST invoice.
Frequently asked questions
How do I calculate 18% GST on ₹10,000?
GST = 10,000 × 18 ÷ 100 = ₹1,800. The total with GST is ₹11,800. Within the same state it's split as ₹900 CGST + ₹900 SGST; for another state it's ₹1,800 IGST.
How do I remove GST from a price that includes it?
Price before GST = inclusive price × 100 ÷ (100 + GST rate). For ₹11,800 at 18%: 11,800 × 100 ÷ 118 = ₹10,000, so the GST is ₹1,800.