GST Calculator

About the GST Calculator

The GST Calculator adds Goods and Services Tax to a pre-tax amount. Enter the base price and choose a GST rate to see the GST amount and the final price you or your customer will pay. It is useful for small businesses, invoices, quotations and quick price checks.

How to use the GST Calculator

1. Enter the amount before GST in rupees.
2. Choose the GST rate.
3. Click Calculate to see the GST amount and the total price.

Frequently asked questions

How is GST calculated?

GST amount = base amount × GST rate ÷ 100. Final price = base amount + GST amount.

Is this a substitute for professional tax advice?

No. It is a quick calculator for estimates. Check current GST rules and consult a tax professional for filings and invoices.

How the GST Calculator works

This calculator adds GST to a price that is before tax. It computes GST amount = (amount × rate) ÷ 100 and final price = amount + GST. Choose the rate that applies to your product or service from the drop-down list.

If you already have a tax-inclusive price and want to find the price before GST, divide by (1 + rate ÷ 100). For example, ₹11,800 inclusive of 18% GST has a base price of 11,800 ÷ 1.18 = ₹10,000.

On an invoice, GST is split depending on the type of sale. For a sale within the same state, half of the GST is charged as CGST and half as SGST. For a sale between states, the full amount is charged as IGST.

Worked examples

Example 1: A product costs ₹10,000 before tax and attracts 18% GST. GST = ₹1,800 and the final price = ₹11,800. In a same-state sale this is ₹900 CGST and ₹900 SGST.

Example 2: An item priced at ₹2,400 with 5% GST has GST of ₹120, so the final price is ₹2,520.

Tips and common mistakes

• GST rates are set by the GST Council and can change. Since 22 September 2025, most goods and services fall under 5% or 18%, with a 40% rate for certain luxury and sin goods and a 0% rate for exempt items. Always confirm the rate for your exact item through its HSN or SAC code.
• Do not apply GST twice. If a price already says "inclusive of GST", use the reverse formula instead.
• Some products carry special rates, such as gold and precious metals, so the drop-down list does not cover every case.
• Keep invoices with the correct GSTIN, HSN or SAC code and tax split. This calculator is meant for quick estimates, not for filing returns.

More questions about the GST Calculator

How do I calculate GST from a tax-inclusive price?

Divide the inclusive price by 1 plus the GST rate as a decimal. For 18% GST, divide by 1.18. The difference between the two amounts is the GST.

What is the difference between CGST, SGST and IGST?

CGST goes to the central government and SGST to the state government when the buyer and seller are in the same state. IGST is charged on sales between different states and goes to the central government, which then shares it with the destination state.

Which GST rate should I choose?

The rate depends on the product or service. Check the current rate notification or ask your accountant. The GST Council decides rates, and they can be revised.

Can I use this for my GST return?

No. It is a quick estimation tool. Returns need invoice-level data, input tax credit and compliance details.

Related tools

• Percentage Calculator – general percentage maths
• Discount Calculator – find the final price after a discount
• Profit & Loss Calculator – check your margin on a sale
• Number to Words – write an invoice amount in words

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