GST Calculator: how to use it
Add or remove GST from a price at 0, 5, 12, 18, 28 or a custom rate, with the formulas and a CGST/SGST split explained.
Goods and Services Tax is added to most purchases in India, and shopkeepers, freelancers and small businesses constantly need to move between two prices: the price before tax and the price including tax. The GST Calculator does both calculations and shows the tax amount and the central and state halves.
It is an estimator for everyday use. Your invoice and your accountant remain the authority on what applies to a particular supply.
How to use the GST Calculator
- Enter the Amount.
- Choose the GST rate: 0%, 5%, 12%, 18%, 28% or Custom rate and type your own percentage.
- Choose what the amount represents: Price before GST (exclusive) or Price including GST (inclusive).
- Press Calculate GST.
- Read the base amount, the GST amount, the total including GST and the CGST / SGST split.
Tips for better results
- If the amount is before tax, GST = amount x rate / 100 and the total = amount + GST. Example: Rs 1,000 at 18% is Rs 180 tax, Rs 1,180 total.
- If the amount already includes tax, the base = amount x 100 / (100 + rate). Rs 1,000 including 18% GST is a base of about Rs 847.46 and tax of Rs 152.54.
- Do not calculate tax-inclusive prices by taking 18% off the total. That gives the wrong base, because the tax was added on the smaller amount.
- For sales within one state, the tax is shared equally between CGST and SGST. For sales between states, the whole amount is IGST.
Always check the current rate
GST rates and the category of each product or service are set by the GST Council and have changed over time. This tool does not know which rate applies to your item, so confirm it on the official GST portal or with your tax advisor before you issue an invoice.
Frequently asked questions
Is this tax advice?
No. It is a calculator for estimates. Confirm rates and rules with an accountant or official sources.
Can I use it for VAT in another country?
Yes, if you choose Custom rate. The percentage arithmetic is the same.
What is the CGST / SGST figure?
It is the total GST divided into two equal halves for sales inside one state.
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