How to use it
- 1Type the amount. Commas are fine: 1,25,000 works.
- 2Pick the GST rate: 5%, 18% or 40%, the special 3% and 0.25% rates, or type any other rate. The old 12% and 28% rates are there for older bills.
- 3Choose whether the amount is before GST (to add tax to a price) or includes GST (to find the value inside an MRP or a total).
- 4Choose whether the sale is within your state (CGST + SGST) or to another state (IGST). The total is the same; only the split changes.
The two formulas
Adding GST (the amount is the price before tax):
- GST = amount × rate ÷ 100
- Total = amount + GST
Removing GST (the amount already includes tax):
- Value before GST = amount × 100 ÷ (100 + rate)
- GST = amount − value before GST
| You have | Rate | Value before GST | GST | Total |
|---|---|---|---|---|
| ₹10,000 before GST | 18% | ₹10,000.00 | ₹1,800.00 | ₹11,800.00 |
| ₹10,000 including GST | 18% | ₹8,474.58 | ₹1,525.42 | ₹10,000.00 |
| ₹2,500 before GST | 5% | ₹2,500.00 | ₹125.00 | ₹2,625.00 |
| ₹2,500 including GST | 5% | ₹2,380.95 | ₹119.05 | ₹2,500.00 |
| ₹60,000 before GST (gold) | 3% | ₹60,000.00 | ₹1,800.00 | ₹61,800.00 |
Pricing with GST in mind
If your customers are consumers, they compare the final price, so decide the shelf price first and use “including GST” to see what you actually keep. If your customers are registered businesses, they claim the GST back as input tax credit and compare the price before tax, so quote that and let the invoice add the tax.
From the figure to the bill
A calculator gives you one number; a bill needs the rest: your GSTIN, the customer’s details, HSN codes, the tax split per line and the total in words. When the figures look right, make the bill with our GST invoice format, which uses the same rounding as this page, or send a quotation first.
Questions people ask
How do I add GST to a price?
GST = price × rate ÷ 100, and total = price + GST. For a price of ₹10,000 at 18%: GST = 10,000 × 18 ÷ 100 = ₹1,800, so the total is ₹11,800. Within a state that ₹1,800 is shown as CGST ₹900 and SGST ₹900.
How do I remove GST from an amount that already includes it?
Value before GST = amount × 100 ÷ (100 + rate). For ₹11,800 including 18% GST: 11,800 × 100 ÷ 118 = ₹10,000, and the GST inside it is ₹1,800. A common mistake is to take 18% of ₹11,800, which gives ₹2,124 and is wrong: GST is charged on the value before tax, not on the total.
What are the GST rates now?
Since 22 September 2025 the main rates are 5% and 18%, with 40% on a short list of luxury and sin goods and nil on essentials. Special rates continue for a few goods, such as 3% on gold and jewellery and 0.25% on rough diamonds. The 12% and 28% slabs were removed on that date; most 12% items moved to 5% and most 28% items to 18%. Check the rate for your own HSN or SAC code before billing.
What is the difference between CGST, SGST and IGST?
When the supplier and the place of supply are in the same state, the tax is split equally into CGST for the Centre and SGST for the state (UTGST in a union territory without a legislature). When the sale goes to another state, the whole tax is charged as IGST. The total tax is the same either way.
Why is my CGST and SGST one paisa apart?
When you take GST out of an inclusive amount, the tax inside it can be an odd number of paise, which cannot be halved equally. The calculator keeps your total exactly as typed and puts the odd paisa in SGST. When you add GST to a price, each half is rounded on its own and the two are always equal, which is how a tax invoice is made.
Does a composition dealer use this?
No. A business under the composition scheme does not charge GST to the customer and issues a bill of supply, not a tax invoice. It pays a small percentage of turnover from its own pocket.
Is the amount I type stored anywhere?
No. The calculation runs in your browser. Only the rate and the two choices you made are remembered on your device for next time; the amount is not.
Last reviewed: 19 September 2026