GST Calculator
Add GST to a base price, or work backwards from a GST-inclusive total to find the tax and net amount, at any rate you enter.
How to use the GST Calculator
- Enter the amount.
- Choose whether that amount already includes GST or not.
- Pick or type the rate and read the base amount, tax amount and total.
About the GST Calculator
The reverse calculation is where most errors happen: taking 18% off an inclusive price is not the same as dividing by 1.18, and using the wrong one leaves your invoice out by a few percent. This tool handles both directions explicitly and shows the base amount and tax component on separate lines so you can copy them straight into an invoice or a return.
Please note: this is an educational estimator. It does not account for processing fees, insurance bundling, prepayment penalties, floating-rate resets or local tax rules, so the figure on a real agreement will differ. Use it to compare options, then confirm with your lender or a licensed financial adviser. Full disclaimer.
Frequently asked questions
How do I remove GST from an inclusive price?
Divide the total by (1 + rate/100). At 18%, divide by 1.18 — subtracting 18% gives the wrong answer.
Which GST rates can I use?
Any. The common slabs are preset, and you can type a custom rate for VAT or sales tax in other countries.
Does it split CGST and SGST?
It gives the total tax; for an intra-state Indian invoice, halve that figure between CGST and SGST.
What is the difference between inclusive and exclusive GST?
Exclusive means the price is before tax and GST is added on top. Inclusive means the price already contains the tax and has to be worked backwards out of the total. Choosing the wrong one is the most common invoicing mistake, so the tool does both explicitly.
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