GST Calculator (Goods and Services Tax)

What is a GST calculator?

GST (Goods and Services Tax) is the tax you pay on most things you buy in India, and the tax a business collects when it sells. A GST calculator tells you how much tax is in a price, or how much to add to it.

You can use it two ways:

• Add GST: you have a price before tax and want the final price. Useful when you send an invoice.
• Remove GST: you have a total that already includes tax and want the original price. Useful when you check a bill.

It’s handy for freelancers, shop owners, small businesses, accountants and shoppers who just want to understand what they’re paying.

How GST rates work in India now

India’s GST structure was simplified in September 2025 (often called GST 2.0). The main rates today are:

The old 12% and 28% slabs were mostly removed, and items were moved to 5%, 18% or 40%. Some things you may have heard of: air conditioners and large TVs moved from 28% to 18%, and many packaged foods and everyday items moved to 5%.

Always check the rate for your exact product or service. The rate depends on its HSN code (for goods) or SAC code (for services). You can check the official rate list on the GST portal or ask your CA.

How to use this GST calculator

1. Choose Add GST or Remove GST.
2. Enter the amount in ₹.
3. Pick the GST rate, or type a custom rate.
4. Click Calculate.

You’ll see the GST amount, the CGST and SGST split, and the final or original price.

Tip: If you’re a freelancer or agency billing for software, design or consulting services, the rate is usually 18%. Still confirm the SAC code for your service.

GST formulas

Adding GST

• GST amount = Price × GST% ÷ 100
• Final price = Price × (1 + GST% ÷ 100)

Removing GST

• Original price = Final price ÷ (1 + GST% ÷ 100)
• GST amount = Final price − Original price

Quick shortcut for removing GST: GST amount = Final price × Rate ÷ (100 + Rate)

Examples you can try

1. Adding 18% GST (an invoice)

Anjali runs a design studio in Mumbai and bills ₹50,000 for her services.

• GST at 18%: ₹9,000
• Total invoice: ₹59,000

2. Removing 18% GST (checking a bill)

You paid ₹11,800 and the price includes 18% GST.

• Original price: ₹11,800 ÷ 1.18 = ₹10,000
• GST included: ₹1,800

3. Removing 5% GST

A bill is ₹5,250 including 5% GST.

• Original price: ₹5,000
• GST included: ₹250

4. Adding 40% GST

A product costs ₹1,00,000 before tax and falls in the 40% slab.

• GST: ₹40,000
• Total: ₹1,40,000

A common mistake when removing GST

Many people take the total and subtract 18% of it. That gives the wrong answer.

For ₹11,800 including 18% GST:

• Wrong way: 11,800 − 18% of 11,800 = 11,800 − 2,124 = ₹9,676
• Right way: 11,800 ÷ 1.18 = ₹10,000

The GST is calculated on the original price, not on the total. That’s why you divide by 1.18, not subtract 18%.

CGST, SGST and IGST: what’s the difference?

GST is split in different ways, depending on where the sale happens.

• CGST (Central GST) + SGST (State GST): used when the seller and buyer are in the same state. The tax is split equally. For 18% GST, that’s 9% CGST + 9% SGST. On ₹1,000, it’s ₹90 + ₹90.
• IGST (Integrated GST): used when the sale crosses state lines. The full rate goes in one tax. For 18%, it’s 18% IGST.

The total tax is the same either way. Only the labels and who receives it differ. This calculator shows the CGST and SGST split, but it can’t decide which one applies to your sale. That depends on where the supply is made.

Who needs to register for GST?

In general, a business must register once its yearly turnover crosses a set limit. The usual limits are around ₹40 lakh for goods sellers and ₹20 lakh for service providers, and they are lower in some special category states. Some businesses must register no matter how small they are, such as many who sell through e-commerce platforms or make certain inter-state supplies. Rules differ by case, so check with your CA or the GST portal before you decide.

What is input tax credit (ITC)?

If you run a registered business, you pay GST on what you buy, and you collect GST on what you sell. Input tax credit lets you subtract the GST you paid on business purchases from the GST you owe. That way, tax isn’t charged twice along the supply chain.

ITC has conditions. You generally need a valid tax invoice, the goods or services must be for business use, and your supplier must have filed their return. Some items are blocked. Ask your CA what applies to you.

GST inclusive vs GST exclusive

• GST exclusive: the price shown is before tax. GST will be added on top.
• GST inclusive: the price shown already contains the tax.

If a shop says “₹1,180 inclusive of 18% GST”, the real price is ₹1,000 and ₹180 is tax. Use the “Remove GST” mode to find the original price.

Frequently Asked Questions