About this calculator
Use “Add GST” when you know the price before tax and want the invoice total. Use “Remove GST” when you have a price that already includes GST, such as an MRP or a bill total, and want to know the tax inside it.
How to use it
- Choose Add GST or Remove GST.
- Enter the amount.
- Pick the GST rate for your goods or service, or choose “Other rate”.
- Choose whether the supply is within one state or between two states to see the correct split.
The formula
- amount
- the taxable value, before GST
- rate
- the GST rate in percent
- inclusive price
- a price that already contains GST
Removing 18% GST is not the same as subtracting 18%: ₹118 minus 18% is ₹96.76, but the price before GST is ₹100.
Worked example
Adding and removing 18% GST
- Add: a service priced at ₹25,000 before tax. GST = 25,000 × 18 ÷ 100 = ₹4,500. Invoice total = ₹29,500.
- Within one state that ₹4,500 is ₹2,250 CGST plus ₹2,250 SGST. Between states it is ₹4,500 IGST.
- Remove: a bill of ₹11,800 that includes 18% GST. Price before GST = 11,800 × 100 ÷ 118 = ₹10,000, so the GST inside is ₹1,800.
What the result means
The CGST and SGST split does not change how much tax the buyer pays; it only decides which government the tax goes to. A registered buyer can usually claim input tax credit for GST paid on business purchases, subject to the conditions in the law.
Rates are decided by the GST Council and are revised from time to time. From 22 September 2025 most goods and services were moved into two main slabs, 5% and 18%, with a 40% rate for a small list of items. The rate for a specific product depends on its HSN or SAC code, so check it before you raise an invoice.
Assumptions
- A single GST rate applies to the whole amount.
- The amount entered is the taxable value, or for Remove GST the full inclusive price.
- No compensation cess, TCS or other levies are included.
Limitations
- This calculator does not decide which rate applies to your goods or service. That depends on the HSN or SAC classification and on current notifications.
- Composition scheme taxpayers pay tax differently and cannot charge GST on their invoices.
- Invoices round tax to the rupee or paise under their own rules, so totals can differ by a paisa or two.
Frequently asked questions
How do I calculate GST backwards from a total?
Divide the total by (100 + rate) and multiply by 100. For 18%, divide by 1.18. The difference between the total and that figure is the GST included.
When is IGST charged instead of CGST and SGST?
IGST applies when the supplier and the place of supply are in different states or union territories, and on imports. CGST plus SGST applies when both are in the same state.
Are the 12% and 28% slabs still used?
From 22 September 2025 most items that were at 12% or 28% moved to 5%, 18% or 40%. Some special rates remain for specific goods. Use “Other rate” for any rate not in the list, and confirm the rate for your item from official sources.
Is GST charged on the MRP?
The MRP printed on a retail pack already includes GST. To find the tax inside it, use Remove GST with the MRP.
For information only. Tax results depend on the law in force, the tax period and your circumstances, and rates are revised from time to time. This is not tax advice. Please confirm the applicable rate and treatment with a qualified professional or the official notifications.
Last reviewed on 29 September 2026. Found a mistake? Tell us.