GST calculator: add or remove GST in one step
Type an amount, pick a rate and the GST calculator shows the tax, the total and the split. Use Price before GST to add tax to a base price. Use Price including GST to work out the price before tax from an MRP or a bill (reverse GST). For a sale inside one state the tax is shown as CGST + SGST, each half of the rate. For a sale to another state it is shown as IGST. Your numbers stay in this tab.
GST formula with examples
| What you want | Formula | Example at 18% |
|---|---|---|
| Add GST | GST = amount × rate ÷ 100 | ₹1,000 → GST ₹180, total ₹1,180 |
| Remove GST (inclusive price) | Base = price ÷ (1 + rate ÷ 100) | ₹1,180 → base ₹1,000, GST ₹180 |
| Same-state split | CGST = SGST = GST ÷ 2 | ₹180 → ₹90 CGST + ₹90 SGST |
| Inter-state | IGST = full GST | ₹180 IGST |
At 5%, ₹2,000 carries ₹100 GST (₹50 CGST + ₹50 SGST). At 40%, ₹10,000 carries ₹4,000 GST.
Current GST slabs (for context)
From 22 September 2025 the commonly described structure is 5% and 18% as the main slabs, 40% for specified luxury and sin goods, plus nil and special rates (such as 3% on gold). Rates belong to HSN/SAC codes and can change, so always use the rate on your invoice or the GST portal. The buttons above are shortcuts, not a ruling.
When to use it
- Check the GST line on a bill or a quotation.
- Turn an inclusive MRP back into the taxable value.
- Split a tax figure into CGST and SGST before you write an invoice.
Tips
- CGST and SGST are each half of the total. If a paisa rounds, trust the total GST.
- Making a bill? Put the figures into the invoice generator and add your GSTIN in the notes.
- Need the amount in words for a cheque or invoice? Use number to words in the Indian lakh–crore system.
This is arithmetic, not tax or legal advice.
Related tasks
The percentage calculator handles margins and discounts. The HRA calculator estimates your rent exemption. For UK, EU or Gulf prices, use the VAT calculator.