How the GST calculator works
Goods and Services Tax (GST) is charged as a percentage of the value of most goods and services sold in India. This calculator works in two directions. Add GST takes a price before tax and works out the GST and the final price. Remove GST takes a price that already includes GST, such as an MRP or a total on a bill, and works backwards to the original value and the tax inside it.
GST formulas in plain words
Add GST: GST = Amount × Rate ÷ 100, Total = Amount + GST Remove GST: Net = Amount × 100 ÷ (100 + Rate), GST = Amount − Net
For a sale within the same state, the GST is split equally into CGST (central) and SGST (state) or UTGST in union territories. For a sale between two states, the full amount is charged as IGST.
Worked examples
- Adding GST: a service worth ₹10,000 at 18% attracts GST of ₹1,800 (CGST ₹900 + SGST ₹900). The invoice total is ₹11,800.
- Removing GST: a product sold for ₹11,800 including 18% GST has a net value of 11,800 × 100 ÷ 118 = ₹10,000, and the GST inside it is ₹1,800.
A common mistake is to take 18% off ₹11,800 directly (which gives ₹2,124). That is wrong, because the tax was calculated on ₹10,000, not on ₹11,800.
Current GST rates
Since 22 September 2025, most goods and services fall under two main rates, 5% and 18%, with a 40% rate for a short list of luxury and "sin" goods. The older 12% and 28% slabs are still available here for checking past invoices and the few items that still use them, and 3% applies to gold and some jewellery. Choose "Other" to enter any rate. Always confirm the rate for your specific product or service code (HSN or SAC) with official sources or your tax adviser.
Tips for businesses
- Show the taxable value, the rate and the CGST/SGST or IGST amounts separately on every tax invoice.
- Keep invoices to claim input tax credit on the GST you pay on business purchases.
- Use the table above to compare how the same price looks at each GST rate.
Frequently asked questions
How do I calculate GST on an amount?
Multiply the amount by the GST rate and divide by 100. For ₹5,000 at 18%, GST = 5,000 × 18 ÷ 100 = ₹900, and the total is ₹5,900.
How do I remove GST from a price that includes it?
Divide the price by (100 + rate) and multiply by 100. For ₹5,900 including 18% GST, the net amount is 5,900 × 100 ÷ 118 = ₹5,000 and the GST is ₹900.
What are CGST, SGST and IGST?
For sales within a state, GST is split equally into CGST (collected by the centre) and SGST or UTGST (collected by the state or union territory). For sales between states, the whole tax is charged as IGST.
What are the GST rates in India now?
From 22 September 2025 the main rates are 5% and 18%, with 40% on certain luxury and sin goods, and special rates such as 3% on gold. Some older invoices use 12% or 28%. Check the rate for your exact product or service.
Is this GST calculator free to use for invoices?
Yes. It is free with no signup, and the Copy button gives you a clean summary you can paste into an invoice or message. It is a calculation aid, not a GST filing tool.