GST Calculator — Add or Remove GST (CGST, SGST, IGST)

Quick answer

To add GST, multiply the price by the rate: ₹10,000 at 18% means ₹1,800 GST and ₹11,800 total. To remove GST from a price that already includes it, divide by (1 + rate/100): ₹11,800 ÷ 1.18 = ₹10,000 base and ₹1,800 GST. For a sale within your state, split the tax equally into CGST and SGST; for a sale to another state, charge the full amount as IGST.

How to use this GST calculator

The calculator has four inputs. Each one changes the result in a specific way, so it helps to know what each field does before you rely on the numbers for an invoice or a quote.

1. Amount — type the figure you have in hand. This can be your selling price before tax, or a price a customer or supplier has quoted that already includes GST.
2. GST rate — pick the rate that applies to your product or service. The list shows the current slabs (18%, 5%, 40%), the special rates (3% for gold and silver, 0.25% for rough diamonds), 0% for exempt items, and the old 12% and 28% slabs for working on invoices dated before 22 September 2025.
3. The amount is — choose Before GST — add GST if the amount is your base price, or Including GST — remove GST if the amount is the final price and you want to find the tax hidden inside it.
4. Sale is — choose Within my state when you and the place of supply are in the same state (you get a CGST + SGST split), or To another state when the place of supply is in a different state (you get IGST).

The result shows the amount before GST, the tax lines (CGST and SGST/UTGST at half the rate each, or IGST at the full rate), total GST and the total amount. Figures are shown to two decimal places, which is what you need for an invoice.

If you pick the old 12% or 28% slab, the calculator adds a reminder that these slabs were merged into 5%, 18% and 40% for most items from 22 September 2025. Use them only to check or correct older invoices.

The GST formula explained

There are only two formulas behind every GST calculation. Once you understand them, you can check any bill by hand in a few seconds.

Adding GST to a base price

GST = Base price × Rate ÷ 100
Total = Base price + GST

This is what you use when you have fixed your price and need to raise an invoice. The base price is also called the taxable value.

Removing GST from an inclusive price

Base price = Inclusive price ÷ (1 + Rate ÷ 100)
GST = Inclusive price − Base price

This is what you use when a customer says "I will pay ₹5,000 all-inclusive", or when a retail price (like an MRP) already includes tax and you need the taxable value for your books.

A quick shortcut: the GST share inside an inclusive price is Rate ÷ (100 + Rate). At 18%, that is 18/118, or about 15.25% of the inclusive price. At 5%, it is 5/105, or about 4.76%. It is never simply 18% or 5% of the inclusive figure.

The CGST, SGST and IGST split

The rate you choose is the total GST rate. For an intra-state sale, half goes to the Centre as CGST and half to the state as SGST (or UTGST in a union territory without its own legislature). For an inter-state sale, the full rate is charged as IGST. The total tax is the same either way; only the heads change.

Current GST rates at a glance

From 22 September 2025, GST moved to a simpler structure. Most goods and services now fall in one of two main slabs, with a higher rate for a short list of items. The table below matches the options in the calculator.

The exact rate for your item depends on its HSN code (for goods) or SAC code (for services), and sometimes on conditions such as whether input tax credit can be claimed. Always confirm the rate in the official rate notifications on the CBIC GST website before you print a large batch of invoices.

Worked examples

Each example below follows the same steps the calculator uses. You can type the same numbers into the tool above and match the result.

Example 1: Adding 18% GST on a local service

A Ghaziabad-based designer charges a Noida client ₹25,000 for a website design. Both are in Uttar Pradesh, so the sale is intra-state.

• GST = ₹25,000 × 18 ÷ 100 = ₹4,500
• CGST @ 9% = ₹2,250
• SGST @ 9% = ₹2,250
• Total invoice = ₹25,000 + ₹4,500 = ₹29,500

Example 2: Removing 18% GST from an inter-state bill

A trader in Delhi receives an all-inclusive order of ₹2,36,000 from a buyer in Haryana. The goods attract 18% GST. Because the buyer is in another state, the tax is IGST.

• Base price = ₹2,36,000 ÷ 1.18 = ₹2,00,000
• IGST = ₹2,36,000 − ₹2,00,000 = ₹36,000

The invoice should show a taxable value of ₹2,00,000 and IGST of ₹36,000, not ₹2,36,000 plus tax.

Example 3: Removing 5% GST from a retail price

A shop sells an item taxed at 5% for ₹1,050 including GST. To record the sale correctly:

• Base price = ₹1,050 ÷ 1.05 = ₹1,000
• GST = ₹50, split as CGST ₹25 and SGST ₹25

Example 4: When the numbers are not round

Real prices rarely divide neatly. Suppose a product is priced at ₹999 including 18% GST.

• Base price = ₹999 ÷ 1.18 = ₹846.61 (rounded to paise)
• GST = ₹999 − ₹846.61 = ₹152.39
• CGST and SGST = about ₹76.19 or ₹76.20 each, depending on how your billing software rounds

The calculator shows two decimals so you can carry these figures straight into an invoice. The GST law also allows tax to be rounded off to the nearest rupee, so many businesses round the final tax figure on the invoice.

Example 5: Gold at 3%

A customer pays ₹1,03,000 for gold jewellery, all-inclusive, from a jeweller in the same state.

• Base price = ₹1,03,000 ÷ 1.03 = ₹1,00,000
• GST = ₹3,000, split as CGST ₹1,500 and SGST ₹1,500

Example 6: An item in the 40% slab, sold to another state

A dealer in Maharashtra sells an item that falls in the 40% slab to a buyer in Gujarat for a base price of ₹5,00,000.

• IGST = ₹5,00,000 × 40 ÷ 100 = ₹2,00,000
• Total invoice = ₹7,00,000

Had the same sale been within Maharashtra, the ₹2,00,000 would be split as CGST ₹1,00,000 and SGST ₹1,00,000.

Checking a bill you have received

The calculator is just as useful for checking purchase bills as for making sales bills. Before you pay a supplier or record a bill for input tax credit, run three quick checks:

1. Tax amount — enter the taxable value shown on the bill with the add-GST mode and confirm the tax matches. A difference of more than a rupee or so usually means a wrong rate or a calculation error.
2. Tax head — if the supplier is in your state and delivered to you in your state, the bill should show CGST + SGST. If the supplier is in another state, it should show IGST. Credit taken under the wrong head is a problem for you, not only for the supplier.
3. Rate — compare the rate with the current rate for that HSN or SAC code. Bills still showing 12% or 28% for items that have moved to new slabs should be queried.

CGST + SGST or IGST: how to choose the right option

The "Sale is" field is where most mistakes happen. The choice does not depend on where your customer's head office is, or where you received payment. It depends on two things: the location of the supplier and the place of supply.

Intra-state (CGST + SGST)

When the supplier's registered place of business and the place of supply are in the same state or union territory, charge CGST and SGST (or UTGST). For example, a Ghaziabad shop selling to a customer who takes delivery in Lucknow charges CGST + SGST, because both points are in Uttar Pradesh.

Inter-state (IGST)

When the supplier and the place of supply are in different states, charge IGST. IGST also applies to imports, to exports, and to supplies made to units in a Special Economic Zone, even if the SEZ unit is in your own state.

How place of supply is decided, in short

• Goods that move — generally the place where the movement ends, that is, where the goods are delivered.
• Goods that do not move — generally where the goods are at the time of delivery to the buyer.
• Services to a registered business — generally the location of the recipient as per their registration.
• Services to an unregistered person — generally the recipient's address on record, or the supplier's location where no address is available.

There are many special rules for services such as events, immovable property, transport and telecom. If your case does not fit the simple rules above, get the place of supply confirmed before you invoice, because charging the wrong head creates a refund-and-repay exercise for both you and your customer.

What UTGST means

The union territories without a legislature (Chandigarh, Ladakh, Lakshadweep, Andaman & Nicobar Islands, and Dadra & Nagar Haveli and Daman & Diu) charge UTGST in place of SGST. Delhi, Puducherry and Jammu & Kashmir charge SGST. The amount is the same; only the label changes, which is why the calculator shows "SGST / UTGST".

How GST flows through a business: input tax credit

A GST-registered business does not simply pay the full GST it collects. It can reduce its payment by the GST it has already paid on business purchases. This is called input tax credit (ITC), and it is why getting the base price and tax right on every invoice matters.

Here is a simple illustration. A trader buys goods for ₹1,00,000 plus 18% GST (₹18,000) and sells them for ₹1,50,000 plus 18% GST (₹27,000).

The ₹9,000 is exactly 18% of the value the trader added (₹50,000). You can use the calculator twice — once on the purchase and once on the sale — to see this for your own numbers.

Credit is set off in a fixed order. IGST credit is used first against IGST, then against CGST and SGST. CGST credit cannot be used to pay SGST, and SGST credit cannot be used to pay CGST. This is another reason to choose the right supply type in the calculator.

To claim credit, you generally need a valid tax invoice, the goods or services must have been received, the supplier must have filed their return and paid the tax, and the invoice should appear in your GSTR-2B. Before paying a new supplier, check their GST number with our GSTIN checker.

Special cases the calculator does not handle on its own

The calculator does one thing well: it works out tax on a single amount at a single rate. Some situations need an extra step before you use it.

Composition scheme dealers

A business under the composition scheme pays tax at a fixed low rate on its turnover and cannot charge GST to customers on its bills. It also cannot claim input tax credit. If you are a composition dealer, do not use the "add GST" option to raise a customer bill — issue a bill of supply instead.

Reverse charge

For certain notified goods and services (for example, some legal services and goods transport services supplied to businesses), the buyer pays the GST directly to the government instead of the supplier. The tax amount is worked out the same way, so the calculator still gives the right figure, but the invoice will not collect it from the buyer.

Exports

Exports are zero-rated. A registered exporter can either supply without paying IGST under a Letter of Undertaking (LUT) or pay IGST and claim a refund. If you export under LUT, there is no tax on the invoice at all.

Mixed-rate invoices

If one invoice has items at different rates (for example, some at 5% and some at 18%), calculate each line separately and then add them up. Never apply an average rate to the invoice total.

Discounts and extra charges

A discount shown on the invoice at the time of sale reduces the taxable value, so apply GST after the discount. Charges such as packing, delivery or installation that are part of the same supply are usually added to the taxable value before GST is calculated.

Old-rate invoices

Invoices issued before 22 September 2025 carry the rates in force at that time. If you are reconciling or correcting such invoices, use the 12% or 28% option. For anything issued now, choose the current rate for your HSN or SAC code.

Quoting prices: GST-inclusive or GST-extra?

How you quote a price decides which mode of the calculator you will use, and it can change how much you actually earn on a deal.

Selling to businesses

Business buyers who are registered usually expect prices "plus GST", because they will claim the tax back as input tax credit. Quote your base price, then use the add-GST mode to show the tax and total. This keeps your margin fixed whatever the rate.

Selling to consumers

Consumers care about the final price they pay. Retail prices are usually shown inclusive of all taxes. If you set a round consumer price like ₹499 or ₹1,999, use the remove-GST mode to see how much of it is actually your revenue.

Why "all-inclusive" deals need care

Suppose you agree to a job for "₹50,000" without saying whether GST is extra. If the client later treats it as inclusive, your actual revenue at 18% is ₹50,000 ÷ 1.18 = ₹42,372.88, with ₹7,627.12 going to GST. That is a large gap on one job. Always write "plus GST as applicable" or "inclusive of GST" in your quotation, and run both modes of the calculator before you agree a price.

What a GST invoice must show

Once the calculator has given you the base price and tax, those numbers have to be placed on a proper tax invoice. A registered supplier's tax invoice should generally include:

• Your name, address and GSTIN
• A serial number unique for the financial year, and the date of issue
• The buyer's name, address and GSTIN (if registered)
• HSN code for goods or SAC code for services
• Description, quantity and unit of each item
• Taxable value of each item, after any discount
• Rate and amount of tax, shown separately as CGST, SGST/UTGST or IGST
• Place of supply, with the state name, for inter-state supplies
• Whether tax is payable on reverse charge
• Signature or digital signature of the supplier or an authorised person

The tax lines on the invoice should be exactly the lines the calculator produces — two lines for an intra-state sale, one line for an inter-state sale. Businesses above the notified turnover threshold must also generate e-invoices through the government's invoice registration portal, which validates these same fields.

Advances received

If you receive an advance for services, GST becomes payable on the advance when you receive it, and you should issue a receipt voucher. For goods, GST on advances is generally not payable at the time of receipt; tax is paid when the invoice is issued. If you receive an all-inclusive advance for a service, use the remove-GST mode to find the tax part.

Common mistakes when calculating GST

• Taking 18% of an inclusive price. On ₹1,180 including 18% GST, the tax is ₹180, not ₹212.40. Always use the remove-GST option for inclusive prices.
• Charging CGST + SGST on an inter-state sale. Tax paid under the wrong head does not count. The supplier has to pay the correct tax and then claim back the wrong one, and the buyer's credit gets stuck in between.
• Using the buyer's billing address to decide the state when the goods are actually delivered somewhere else. For goods, delivery location usually decides the place of supply.
• Applying an old slab to a new invoice. The 12% and 28% slabs were merged for most items. Check your current rate before quoting.
• Splitting IGST into halves. IGST is a single tax at the full rate. Only intra-state supplies are split.
• Charging GST without being registered. Only a registered person can collect GST. If you are not registered, you cannot add GST to your bill.
• Applying one rate to a mixed invoice. Every line item takes its own rate.

Do you need GST registration?

You can charge GST only after you have a GSTIN. Registration is required once your aggregate turnover in a financial year crosses the threshold for your state and type of business.

Some states have chosen the lower limits, so check the limit that applies to yours. Certain businesses must register regardless of turnover — for example, those making inter-state supplies of goods, selling through e-commerce operators that collect tax, or required to pay tax under reverse charge. Voluntary registration is also allowed, and many small businesses take it so that their business customers can claim input tax credit.

If you are close to the limit or selling to other states, our GST registration service can get your GSTIN set up with the right business category and place of business.

From calculation to filing: what happens next

The figures you calculate here feed directly into your GST returns. Each invoice's taxable value and tax (split into CGST, SGST and IGST) is reported in GSTR-1, and the total tax payable after credit is paid through GSTR-3B.

Due dates are sometimes extended by the government, so check the GST portal each month. Late filing attracts a late fee and, if tax is paid late, interest.

Documents to keep ready

• Sales invoices showing taxable value, rate, and tax under each head
• Purchase invoices from registered suppliers, with their GSTIN
• Your GSTR-2B for the month, to match purchase invoices
• Credit and debit notes for returns, discounts or price changes
• E-way bills for goods movement where applicable
• Bank statements to match receipts and payments

GST and your income tax return

GST you collect is not your income. If you are registered and claim input tax credit, your profit and loss account should show sales and purchases without GST. If you are not registered or cannot claim the credit, the GST you pay on purchases becomes part of your cost.

Turnover reported in your GST returns and in your income tax return should match, after adjusting for timing differences. The income tax department can see GST turnover data, and large gaps can lead to questions. If you run a small business under presumptive taxation, our presumptive tax 44AD calculator works on turnover before GST.

Get it checked by an expert

A wrong rate or a wrong tax head on one invoice can block your customer's credit and cost you a correction later. TaxCaller's GST expert can confirm the right HSN or SAC rate for your products, check the CGST, SGST and IGST split on your invoices, and handle your GST registration and monthly returns. The fee is told to you upfront before any work starts, and your first call is free.