GST Calculator Online India – Add & Remove GST | Fayro
GST Calculator Online India: Add or Remove GST Instantly
You get a quote that says ₹11,800 and the seller tells you "GST is included". Or you are making your own invoice and you are not sure whether to add 18% on top of the price or take it out of the total. Everyone gets this wrong at least once, and it is not because the maths is hard. It is because it is easy to apply the rate in the wrong direction.
The GST calculator on Fayro does this for you. In this post I will explain how GST is worked out, show a few examples with real numbers, and point out the mistakes people make most often.
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GST in simple words
GST is the tax added on most goods and services sold in India. As a customer, you see it as an extra line on the bill. As a seller, you collect it and pass it on to the government.
For a sale inside one state, the tax is split equally into CGST and SGST. For a sale between two states, the whole amount is charged as IGST. The total tax is the same either way. Only the labels on the invoice change.
Which GST rates apply right now?
The system was simplified on 22 September 2025. Today most goods and services fall under 5% or 18%. Items that are luxury or harmful to health, such as aerated drinks, large cars and online gaming, are taxed at 40%. Many basic items, like fresh vegetables and plain milk, are at 0%. A few things keep a special rate of their own, for example gold and jewellery at 3%.
The old 12% and 28% slabs are no longer the main rates, so if you are following an older guide, the numbers may be out of date. Rates for a particular product can still change, so always check the exact rate on your invoice or on the official GST website (gst.gov.in).
How to add GST to a price
Use this when you have the price before tax and want to know the final amount.
- GST amount = price × rate ÷ 100
- Final price = price + GST amount
Example: a product costs ₹10,000 and the rate is 18%. GST is ₹1,800, so the final price is ₹11,800. For a sale within the state, that is ₹900 CGST and ₹900 SGST.
Another one: ₹2,000 at 5% gives ₹100 GST, and the final price is ₹2,100.
How to remove GST from a total
Use this when the price you have already includes tax, and you want to know how much of it is GST.
- Price before GST = total × 100 ÷ (100 + rate)
- GST amount = total − price before GST
Example: the total is ₹11,800 and it includes 18% GST. The price before GST is 11,800 × 100 ÷ 118, which is ₹10,000. The GST inside it is ₹1,800.
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The mistake almost everyone makes
When the total already includes GST, many people multiply it by the rate directly. With ₹11,800 at 18% that gives ₹2,124, which is wrong. The correct GST is ₹1,800. The reason is simple: the 18% was charged on ₹10,000, not on ₹11,800. If your numbers look a little too high, this is usually why.
How to use the Fayro GST calculator
- Open the GST calculator. It works on a phone as well as a laptop.
- Enter the amount.
- Choose the GST rate that applies to your item.
- Tell the calculator whether the amount you entered is before GST or already includes it, if the page asks.
- Read the GST amount and the final price.
Fayro calculators update as you type, and the numbers are worked out on your own device, so nothing you enter is sent anywhere. You can change the amount or the rate and see the result change straight away.
Who finds this useful?
Shopkeepers and small business owners use it to prepare invoices. Freelancers use it to work out how much GST to add to a quote. Students use it to check their accounting homework, and regular customers use it to see how much of a bill is tax. If you are comparing two prices, one with GST and one without, it is the quickest way to make them comparable.
Frequently asked questions
Is the Fayro GST calculator free?
Yes. Fayro tools are free to use, and the site runs on ads.
Do I need to sign up?
No. Open the page and start calculating.
What is the difference between CGST, SGST and IGST?
CGST and SGST are used for sales within one state and share the tax equally. IGST is used for sales between states. The total tax is the same.
What GST rate should I choose?
Choose the rate that applies to your product or service. It is usually printed on the invoice. If you are not sure, check the official GST website or ask your accountant.
Can I use it to make a GST invoice?
It helps you work out the figures. For an official invoice, follow the format and rules that apply to your business.
Is the result exact?
The calculator gives estimates for general information. For tax filing or a big decision, confirm the numbers with an accountant or the official source.
Give it a try
Take a bill you have lying around and check it with the free GST calculator. You will know in a few seconds whether the tax on it is right. If you also need other calculations, there are more tools in the calculators section of Fayro.