GST Calculator – Add or Remove GST Instantly

GST Calculator for Inclusive and Exclusive Prices

Use this free GST calculator to add GST to a base price or remove GST from a tax-inclusive amount. Select a GST rate and supply type to calculate the pre-GST value, total tax and CGST/SGST or IGST breakup in seconds.

GST Calculator

Calculate GST instantly — add GST to a base price or extract GST from an inclusive price, with CGST/SGST or IGST breakup.

Amount before GST (₹)

GST Rate0.25%3%5%12%18%28%

Total (incl. GST)

₹0

Base Amount (pre-GST)₹0

Total GST₹0

CGST₹0

SGST₹0

For intra-state supply, GST is split equally between CGST and SGST; inter-state supply attracts full IGST. Select a common rate shown above and verify the rate applicable to the HSN/SAC classification. Estimates only.

Reviewed on July 13, 2026 using official CBIC GST rate and supply guidance.

The calculator supports common GST rate options of 0.25%, 3%, 5%, 12%, 18% and 28%. It performs a mathematical tax breakup; the correct rate still depends on the product or service classification, notification, place-of-supply rules and transaction facts.

Quick answer: For an intra-state supply, the selected GST rate is generally divided equally between CGST and SGST. For an inter-state supply, the full rate is shown as IGST. The total tax amount remains the same when the applicable combined rate is the same.

How to use the GST calculator

1. Select Add GST (Exclusive) when the entered amount does not include tax.
2. Select Remove GST (Inclusive) when tax is already included in the entered price.
3. Choose intra-state supply for a CGST and SGST split or inter-state supply for IGST.
4. Enter the amount and select the applicable GST rate.
5. Review the base amount, total GST and tax-head breakup shown instantly.

GST-exclusive priceThe displayed amount is the base value before GST. Tax is added to find the final invoice amount.

GST-inclusive priceThe displayed amount already contains tax. The calculator extracts the embedded GST and base value.

GST calculation formulas

Adding GST to an exclusive amount

GST amount = Base amount × GST rate ÷ 100

Final price = Base amount + GST amount

Removing GST from an inclusive amount

Base amount = Inclusive price ÷ (1 + GST rate ÷ 100)

GST amount = Inclusive price − Base amount

GST calculation example at 18%

Example 1: Add GST to ₹10,000

• Base amount: ₹10,000
• GST at 18%: ₹1,800
• Total inclusive amount: ₹11,800
• Intra-state breakup: CGST ₹900 + SGST ₹900
• Inter-state breakup: IGST ₹1,800

Example 2: Extract GST from ₹10,000

When ₹10,000 already includes 18% GST, the pre-GST value is approximately ₹8,474.58 and the embedded GST is approximately ₹1,525.42. Subtracting 18% directly from the inclusive price would not produce the correct base value.

CGST, SGST and IGST explained

Tax type	When it generally applies	Calculator treatment
CGST	Central component of an intra-state supply	Half of the selected combined GST rate
SGST/UTGST	State or Union Territory component of an intra-state supply	Half of the selected combined GST rate
IGST	Inter-state supply and certain deemed inter-state supplies	Full selected GST rate

The supplier's location and the legally determined place of supply decide whether a transaction is intra-state or inter-state. A buyer's postal address alone may not be enough to classify every transaction.

GST rate options available in this tool

Selectable rate	Intra-state split	Inter-state tax
0.25%	0.125% CGST + 0.125% SGST	0.25% IGST
3%	1.5% CGST + 1.5% SGST	3% IGST
5%	2.5% CGST + 2.5% SGST	5% IGST
12%	6% CGST + 6% SGST	12% IGST
18%	9% CGST + 9% SGST	18% IGST
28%	14% CGST + 14% SGST	28% IGST

Rate-classification warning: Do not select a rate only because it is common in your industry. The applicable rate can depend on HSN/SAC classification, description, conditions, exemptions and later notifications. Some supplies may also attract compensation cess or special treatment that this tool does not calculate.

What this calculator does not include

• HSN or SAC classification and rate determination;
• Input tax credit eligibility or blocked credits;
• Reverse-charge liability;
• GST compensation cess;
• TDS or TCS under GST;
• Export, SEZ and zero-rated supply documentation;
• Composite or mixed-supply classification;
• Invoice-level discounts, credit notes and return adjustments; or
• Registration, return filing and payment obligations.

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Frequently asked questions

How do I calculate GST on an exclusive price?

Multiply the base price by the GST rate and divide by 100. Add the resulting GST amount to the base price to get the tax-inclusive total.

How do I remove GST from an inclusive amount?

Divide the inclusive amount by 1 plus the GST rate expressed as a decimal. Subtract the resulting base amount from the inclusive price to find the embedded GST.

Why can I not simply subtract 18% from a GST-inclusive price?

Because 18% GST is calculated on the smaller pre-tax base, not on the higher inclusive total. Use the inclusive-price formula to extract the correct tax amount.

What is the difference between CGST, SGST and IGST?

CGST and SGST/UTGST generally apply together to an intra-state supply. IGST generally applies to an inter-state supply. Place-of-supply rules determine the correct classification.

Is CGST always half of the total GST rate?

For the standard intra-state split used by this calculator, CGST and SGST are shown equally. Verify the applicable notification and transaction treatment for your invoice.

Which GST rate should I select?

Select the notified rate applicable to the goods or services based on the correct HSN/SAC classification and current conditions. The calculator does not determine classification.

Does this GST calculator include input tax credit?

No. It calculates output tax amounts only. Input tax credit depends on eligibility, documentation, supplier compliance and other statutory conditions.

Does the calculator include compensation cess?

No. Compensation cess, where applicable, must be calculated separately using the relevant rate and valuation rules.

Can I use this result directly on a GST invoice?

Use it to check arithmetic, but verify the GSTIN details, place of supply, HSN/SAC, rate, taxable value, reverse-charge status and invoice requirements before issuing a tax invoice.

Official sources

• CBIC – GST rates for goods and services
• CBIC – GST frequently asked questions
• CBIC – Integrated Goods and Services Tax provisions

Disclaimer: This calculator provides arithmetic estimates for education and planning. It does not determine the correct GST classification, rate, place of supply, input tax credit or filing treatment. Verify current notifications or consult a qualified GST professional.