Free Tool

GST Calculator

Add or remove GST from any amount, with the CGST/SGST or IGST split, under GST 2.0 (effective 22 September 2025).

Free
· No signup
· GST 2.0 rates
· Runs in your browser

Private by design. Your calculations are performed locally in your browser and are not uploaded to Q3 Labs.

Result

Enter the amount and the GST rate to see the result.

What is a GST calculator?

A GST calculator works out the Goods and Services Tax on an amount. Give it an amount before tax and a rate, and it adds the GST to find the total. Give it a total that already includes GST, and it works backwards to find the taxable amount and the tax.

Taxable amount: the value of the goods or services before GST.
GST amount: the tax, as a percentage of the taxable amount.
Total amount: taxable amount plus GST.
CGST + SGST/UTGST: the GST split in half for a sale within the same state or UT.
IGST: the full GST amount for a sale between states, or an import.

It is a calculation tool only: it doesn't include compensation cess or other levies, and doesn't file or validate a GST return.

GST formulas

GST amount = Taxable amount × GST rate ÷ 100

Total amount = Taxable amount + GST amount

Taxable amount = Total amount × 100 ÷ (100 + GST rate)

CGST = SGST/UTGST = GST amount ÷ 2 (intra-state)

IGST = GST amount (inter-state)

Adding GST multiplies the taxable amount by (1 + rate ÷ 100). Removing GST from a GST-inclusive total divides by that same factor, rather than simply subtracting the percentage from the total.

GST amount and total for each rate slab on an amount of 10,000
Rate	GST on ₹10,000.00	Total
0%	₹0.00	₹10,000.00
0.25%	₹25.00	₹10,025.00
1.5%	₹150.00	₹10,150.00
3%	₹300.00	₹10,300.00
5%	₹500.00	₹10,500.00
18%	₹1,800.00	₹11,800.00
40%	₹4,000.00	₹14,000.00

CGST, SGST and IGST explained

GST on ₹10,000.00 at 18% comes to ₹1,800.00 either way, but it's split differently depending on where the buyer and seller are:

Same state or UT: split evenly into CGST and SGST/UTGST, ₹900.00 each.
Different states, or an import: charged in full as IGST, ₹1,800.00.

CGST and IGST go to the central government; SGST/UTGST goes to the state or union territory.

GST 2.0 rate slabs

From 22 September 2025, Notification 9/2025-Central Tax (Rate) set goods and services into seven rate slabs: 0%, 0.25%, 1.5%, 3%, 5%, 18%, 40%. The rate that applies depends on the specific goods or service; this calculator doesn't look that up for you, but it accepts any of these slabs or a custom rate.

Worked example: adding GST

An invoice for ₹10,000.00 at 18% GST, within the same state: ₹10,000.00 × 18 ÷ 100 = ₹1,800.00, split into CGST ₹900.00 and SGST ₹900.00, for a total of ₹11,800.00.

Worked example: removing GST

A total of ₹11,800.00 that already includes 18% GST: ₹11,800.00 × 100 ÷ 118 = ₹10,000.00, so the GST portion is ₹1,800.00.

Common GST calculation mistakes

Subtracting the rate from a GST-inclusive total. 18% off a total isn't the same as the taxable amount; divide by (100 + rate) ÷ 100 instead.
Charging CGST + SGST on an inter-state sale. That sale needs IGST instead.
Mixing up the taxable amount and the total. Check whether your starting figure already includes GST.
Forgetting cess or other levies. Calculates GST only; doesn't include compensation cess or other levies. Invoice rounding may differ.

Frequently Asked Questions

How do I calculate GST on an amount?

Multiply the taxable amount by the GST rate and divide by 100. For ₹10,000.00 at 18%: ₹10,000.00 × 18 ÷ 100 = ₹1,800.00, giving a total of ₹11,800.00.

How do I remove GST from a total that already includes it?

Divide the total by (100 + GST rate) and multiply by 100 to get the taxable amount. ₹11,800.00 including 18% GST has a taxable amount of ₹10,000.00 and GST of ₹1,800.00.

What is the difference between CGST, SGST and IGST?

For a sale within the same state or union territory, GST splits into CGST (Central GST) and SGST/UTGST (State/UT GST), each half the total GST amount, both going to a different government. For a sale between two states, or an import, the full GST amount is charged as IGST (Integrated GST) instead.

What are the current GST rates (GST 2.0)?

From 22 September 2025, goods and services sit at 0%, 0.25%, 1.5%, 3%, 5%, 18% or 40%, depending on the item, under Notification 9/2025-Central Tax (Rate). You can also enter a custom rate.

Does this calculator include compensation cess?

Calculates GST only; doesn't include compensation cess or other levies. Invoice rounding may differ.

What if the GST rate is 0%?

A 0% rate adds no GST either way: ₹500.00 stays ₹500.00 whichever direction you calculate.

Is my data stored or sent anywhere?

No. The calculation runs in your browser; the amounts you enter are not uploaded to Q3 Labs, stored, or added to the page address (other than a GST rate shared via a link).

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