GST Calculator
Add GST to a price or pull it back out of a total — with the CGST, SGST, and IGST split worked out for you.
GST amount
₹1,800.00
How to Use
- 1. Enter the amount you want to work from.
- 2. Choose whether that amount excludes or already includes GST.
- 3. Pick a GST rate preset, or type your own.
- 4. Read the tax, the pre-tax base, the total, and the CGST/SGST or IGST split.
Adding vs Removing GST
Adding GST is straightforward: multiply the base price by the rate. Removing it is where mistakes happen. You cannot simply subtract 18% from a GST-inclusive total — the tax was calculated on the smaller base figure, not on the total. The correct extraction is tax = total × rate ÷ (100 + rate).
On a ₹11,800 inclusive total at 18%, that gives ₹1,800 of tax on a ₹10,000 base. Subtracting 18% of the total would have wrongly produced ₹2,124.
The CGST/SGST versus IGST choice only affects how the same tax is presented on the invoice: a sale inside one state splits the levy evenly between the central and state governments, while an inter-state sale is charged as a single integrated line.
Building an invoice? Pair this with our Invoice Generator and Number to Words Converter.
Frequently Asked Questions
What is the difference between GST-inclusive and GST-exclusive?
An exclusive amount is the price before tax — GST is added on top. An inclusive amount already contains the tax, so the tax has to be extracted from it. Choosing the wrong mode is the most common source of invoicing errors.
How do I remove GST from a total?
Switch to "Amount includes GST" and enter the final figure. The tool extracts the tax using amount × rate ÷ (100 + rate), and shows the pre-tax base it came from.
What are CGST, SGST, and IGST?
For a sale within the same state, GST is split evenly into CGST (central) and SGST (state). For a sale between states, the whole amount is charged as a single IGST line instead. The total tax is the same in both cases.
Which GST rate should I use?
Since 22 September 2025 most goods and services are taxed at 5% or 18%, with 40% for a short list of luxury and sin goods and 3% for items such as gold. A few items still carry the older 12% or 28% rates. The correct slab depends on the goods or service, so check the current notified rate for your HSN or SAC code.
Can I use this for VAT or sales tax?
Yes. The arithmetic is identical for any single-rate VAT or sales tax — just type your own rate instead of using a preset.
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Guide
How to add GST to a price or take it out of a GST-inclusive total
This calculator answers one of two questions. Either you have a price before tax and want to know what the customer will pay, or you have a final tax-inclusive figure, such as a shop bill or a supplier's quoted total, and you want to know how much of it is GST and how much is the real price. A toggle at the top, labelled "The amount I entered...", switches between "Excludes GST" and "Includes GST". The result panel then shows the GST amount, the pre-tax base, the CGST and SGST halves (or a single IGST line), and the total.
A note on rates. India restructured GST in September 2025: from 22 September 2025 most goods and services moved to a two-rate structure of 5% and 18%, with a 40% rate for a short list of sin and luxury items and a few special rates such as 3% on gold. The older 12% and 28% slabs were largely removed. The preset buttons in this tool (3, 5, 12, 18, 28, 40) still include the two older values for the few items that retain them, and any other rate can be typed into the rate box. Rates can change again, so confirm the notified rate for your HSN or SAC code with your accountant or the GST portal before invoicing.
Step by step
- Under "The amount I entered..." choose Excludes GST if your number is a price before tax, or Includes GST if it is the final amount that already contains tax.
- Type the figure into the Amount box. It starts at 10,000 and is always treated as rupees.
- Pick a rate with one of the preset buttons, or type any value, including decimals, into the GST rate (%) box beneath them.
- Tick "Inter-state sale (use IGST)" only if the supply crosses state lines. Leave it unticked for a sale within one state.
- Read the GST amount at the top, then Base (pre-tax), the CGST and SGST lines (each at half the rate) or the single IGST line, and the Total at the bottom.
- Change any input to compare scenarios. Results update as you type, so there is no calculate button.
When this is useful
- A small retailer checking the tax portion of a tax-inclusive bill before entering it in a ledger.
- A freelancer or consultant turning a quoted fee into the amount to put on a GST invoice.
- A buyer who has been told "the price is 11,800 all-in" and wants to see the pre-tax figure behind it.
- A bookkeeper reconciling a supplier statement where some lines are inclusive and others exclusive.
- Anyone outside India working with a flat-rate VAT or sales tax, since the arithmetic is identical.
Worked example: A Pune designer invoicing two clients
A designer in Pune quotes 42,500 before tax. With Excludes GST selected and 18% chosen, the tool shows GST of 7,650.00 and a total of 50,150.00. For a Pune client (same state) the tax appears as CGST 9% of 3,825.00 plus SGST 9% of 3,825.00. For a client in Hyderabad she ticks the inter-state box and the same 7,650.00 appears as a single IGST line, with the total still 50,150.00. Later, a different customer pays a flat 5,900 and asks how much of it is tax. Switching to Includes GST at 18% gives a base of 5,000.00 and GST of 900.00, which is 5,900 x 18 / 118.
Tips for better results
- When you are working backwards from a price tag, always choose Includes GST. It is the setting people forget most often.
- Use the CGST and SGST lines to cross-check a bill. Each should equal exactly half of the GST amount.
- Switching the inter-state tick changes only how the tax is presented. The total never changes.
- If you sell several items at different rates, calculate each rate separately and add the results rather than averaging the rates.
Common mistakes
- Subtracting the rate from an inclusive total. Taking 18% off 5,900 gives 1,062 of tax, but the real figure is 900, because the tax was charged on the smaller base. Use the Includes GST mode instead.
- Leaving the mode on Excludes GST while typing a shelf price. The tool will add tax on top of tax. Check the toggle before reading the answer.
- Assuming the preset buttons are current for your product. Twelve and 28 percent are no longer the rate for most items, so verify the slab for your HSN or SAC code.
- Ticking the inter-state option because the customer is in another city. What matters is the state of the supplier and the place of supply, not the distance.
- Expecting the tool to handle cess, reverse charge or tax collected at source. It calculates one rate on one amount and nothing more.
Your files and privacy
The calculation runs in your browser as you type, and the amounts and rate you enter are not sent anywhere or stored. Like the other pages on this site, opening the tool records an anonymous usage event (the tool name and a random session identifier) for traffic statistics, but none of your figures are part of it.
Frequently asked questions
What is the formula for removing GST from an inclusive amount?
Tax equals the total multiplied by the rate and divided by (100 plus the rate). At 18%, that is total x 18 / 118. The base is then the total minus that tax. The tool does this for you whenever Includes GST is selected.
Why are there still 12 and 28 buttons if those slabs changed?
The presets are shortcuts for common numbers, and a few items may still be taxed at those rates, for example specified bricks and tiles at 12% or tobacco products at 28% pending a later change. For most goods and services the standard rates are now 5% and 18%, with 40% for select items. Always confirm your item's rate.
When do I use CGST and SGST, and when IGST?
For a supply within one state the tax is split equally into central and state GST. For a supply between states, or an import or export, it is charged as integrated GST. The tool shows whichever presentation you choose with the inter-state checkbox, and the total is the same either way.
Does this replace a GST invoice?
No. It is a calculator. A valid tax invoice needs details such as GSTIN, invoice number, HSN or SAC code and place of supply. You can use the figures here when preparing one, for example in the Invoice Generator on this site.
Can I use it for VAT or sales tax in another country?
Yes, for any single-rate tax calculated on a price. Type your own rate. The amounts are shown with a rupee sign, so just read them as your own currency.
Guide reviewed 2026-10-11 by the useToolify team.
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