How to use this GST calculator
- Choose Add GST or Remove GST. Add GST when you have a price before tax, for example to raise an invoice. Remove GST when a price already includes tax and you need the base price and the tax inside it.
- Enter the amount in rupees. Under "More options" you can set a quantity, so the amount is treated as a price per unit.
- Pick the GST rate. The list covers the current slabs, the special rates for gold and diamonds, 0%, and the old 12% and 28% slabs for checking older bills. Choose "Custom rate" for anything else.
- Choose the type of supply. Within a state, GST is split into CGST and SGST. Between states, it is charged as IGST. The result updates as you type, and the table below shows the same amount at every rate.
GST formulas
GST = Price × Rate · Total = Price × (1 + Rate) Adding GST to a price before tax. Rate is written as a decimal: 18% = 0.18.
Base price = Inclusive price ÷ (1 + Rate) · GST = Inclusive price − Base price Removing GST from a price that already includes it. Within a state, CGST = SGST = GST ÷ 2.
Worked example
A consultant in Pune bills a client in the same state ₹10,000 for services taxed at 18%. GST is ₹10,000 × 0.18 = ₹1,800, split into ₹900 CGST and ₹900 SGST. The invoice total is ₹11,800. If the client were in Bengaluru instead, the same ₹1,800 would be charged as IGST.
Going the other way, a shop price of ₹11,800 including 18% GST has a base price of ₹11,800 ÷ 1.18 = ₹10,000. The tax is 15.25% of the price you pay, not 18%, because the rate applies to the base, not the total.
GST rates in India after GST 2.0
On 22 September 2025 India moved to a simpler structure, widely called GST 2.0. Most items that used to be taxed at 12% moved to 5%, and most items at 28% moved to 18%. A new 40% rate applies to a narrow group of luxury and sin goods.
| Rate | Typically applies to |
|---|---|
| 0% | Nil-rated or exempt supplies, such as many unprocessed foods and essential items |
| 0.25% | Rough diamonds and some precious stones |
| 3% | Gold, silver and jewellery |
| 5% | Most everyday goods and many services (merit rate) |
| 18% | Standard rate for most other goods and services |
| 40% | Selected luxury and sin goods |
These are broad categories, not a classification guide. The rate for a specific product depends on its HSN code (goods) or SAC code (services), and the GST Council can change rates by notification.
Check old invoices carefully. A bill dated before 22 September 2025 may correctly show 12% or 28%. One dated after usually should not. Select the old slab in the calculator to see what a 12% item costs at 5%, or a 28% item at 18%.
CGST, SGST, UTGST and IGST explained
- CGST (Central GST) and SGST (State GST) apply together on a sale within one state, each at half the rate.
- UTGST replaces SGST in Union Territories without their own legislature, such as Chandigarh or Ladakh.
- IGST (Integrated GST) applies at the full rate on sales between states and on imports, and is shared between the centre and states later.
The total tax is the same either way. What changes is how it appears on the invoice and in your returns, so picking the right type of supply matters for compliance even though the customer pays the same amount.
Common GST mistakes
- Subtracting the rate from an inclusive price. Taking 18% off ₹11,800 gives ₹9,676, not ₹10,000. Always divide by 1.18.
- Using a removed slab. 12% and 28% no longer apply to new supplies after 22 September 2025.
- Charging CGST and SGST on an interstate sale. That should be IGST, and fixing it later means amending returns.
- Rounding each line differently. Work out tax per line or on the total consistently, and round to the paisa or rupee the way your accounting software does.
Paid GST late? Work out the interest with the GST interest calculator. Planning a purchase on credit? Compare EMIs with the loan calculator, which also shows amounts in rupees with lakh and crore grouping when you choose INR.
Frequently asked questions
How do I calculate GST on a price?
How do I remove GST from an inclusive price?
What are the GST rates after GST 2.0?
When do I charge CGST and SGST instead of IGST?
Can I still use 12% or 28% in the calculator?
Is this calculator suitable for filing returns?
Sources and further reading
Independent, official guidance on this topic. Rules differ by country, so check the regulator where you live.
- GST: Central Board of Indirect Taxes and Customs · CBIC, Government of India
- GST portal: returns, payments and rate notifications · Goods and Services Tax Network
This calculator gives estimates for education and planning. It is not financial advice, and your lender's figures may differ. See how we calculate.