GST Calculator
Add or remove GST instantly and see the CGST/SGST split.
Updates as you type. CGST and SGST are each half of the GST.
What is a GST Calculator and How It Works
A GST calculator helps you work out the Goods and Services Tax on any product or service in India. GST is an indirect tax levied on the supply of goods and services, and it replaced multiple older taxes like VAT, service tax and excise duty. The most common GST slabs in India are 5%, 12%, 18% and 28%, though some items are taxed at 0% or special rates. Always verify the current slab for your specific product, as rates can change.
There are two ways people use a GST calculator. The first is adding GST when you have a price that excludes tax (exclusive) and want the final price. The second is removing GST when you already have a tax-inclusive price and want to find the base value and the tax component. For any intra-state sale, the total GST is split equally into CGST (Central GST) and SGST (State GST).
GST Formula: Add GST and Remove GST
The core formula to calculate GST on an exclusive amount is simple:
- GST Amount = (Original Amount × GST Rate) ÷ 100
- Final Price (inclusive) = Original Amount + GST Amount
To remove GST from a price that already includes tax, use:
- Base Amount = Inclusive Price × 100 ÷ (100 + GST Rate)
- GST Amount = Inclusive Price − Base Amount
For intra-state transactions, the tax is divided equally:
- CGST = GST Amount ÷ 2
- SGST = GST Amount ÷ 2
For inter-state transactions, instead of CGST and SGST, a single IGST (Integrated GST) equal to the full GST amount applies.
Worked Example of GST Calculation
Suppose you sell a product for ₹10,000 (exclusive of tax) and the applicable GST rate is 18%.
Adding GST:
- GST Amount = (10,000 × 18) ÷ 100 = ₹1,800
- Final Price = 10,000 + 1,800 = ₹11,800
- CGST = 1,800 ÷ 2 = ₹900, SGST = ₹900
Now suppose a customer paid ₹11,800 inclusive of 18% GST and you want to find the base price.
Removing GST:
- Base Amount = 11,800 × 100 ÷ (100 + 18) = 11,800 × 100 ÷ 118 = ₹10,000
- GST Amount = 11,800 − 10,000 = ₹1,800
This confirms the calculation both ways. The table below shows the GST and final price on a ₹1,000 base across common slabs (verify your slab before filing).
| Base ₹1,000 | GST | Final Price |
| 5% | ₹50 | ₹1,050 |
| 12% | ₹120 | ₹1,120 |
| 18% | ₹180 | ₹1,180 |
| 28% | ₹280 | ₹1,280 |
Why Use an Online GST Calculator
Manually calculating GST, especially removing it from inclusive prices, is error-prone. An online GST calculator gives you instant, accurate results and automatically splits the amount into CGST and SGST. This is useful for small business owners raising invoices, freelancers quoting clients, shoppers checking bills, and accountants reconciling tax. It removes guesswork and helps ensure your invoices and returns are correct. Remember that GST rates and rules are set by the GST Council and can be revised, so always confirm the latest applicable rate for your goods or services.
Frequently Asked Questions
Multiply the amount by the GST rate and divide by 100. For example, GST at 18% on ₹10,000 is (10,000 × 18) ÷ 100 = ₹1,800, making the final price ₹11,800.
Use Base Amount = Inclusive Price × 100 ÷ (100 + GST Rate). For ₹11,800 at 18%, the base is 11,800 × 100 ÷ 118 = ₹10,000, and the GST portion is ₹1,800.
For sales within the same state, GST is split equally into CGST (collected by the central government) and SGST (collected by the state government). Each equals half of the total GST amount.
The main GST slabs are 5%, 12%, 18% and 28%, with some goods at 0% or special rates. The correct slab depends on the product or service, so verify the current rate before applying it.
IGST (Integrated GST) applies on inter-state supplies and imports. It is a single tax equal to the full GST amount, collected by the central government and later shared with states.
GST is calculated on the transaction value, which is usually the selling price (excluding GST) agreed between buyer and seller. The tax is added on top of this base value to arrive at the final invoice amount.