GST / VAT Calculator
Add or remove GST/VAT from a price and get an invoice-ready breakdown of the net amount, the tax, and the gross total. It handles both directions - building a tax-inclusive price and extracting the tax already inside one.
GST / VAT Calculator
Add tax to a base amount or remove tax from an inclusive amount with per-item and bulk totals.
Use Add mode when your price excludes tax. Use Remove mode when your invoice amount already includes GST or VAT and you need the base value.
Useful for checkout validation, invoice preparation, and multi-item tax reconciliation.
Inclusive versus exclusive: the part people get wrong
The most common billing error is treating a tax-inclusive price as if it were exclusive. If an item is priced at 118 including 18% GST, the tax inside it is not 18% of 118. The net is 118 / 1.18 = 100, and the tax is 18. To add tax to a net price you multiply (100 x 1.18 = 118); to remove it from a gross price you divide (118 / 1.18 = 100). Mixing these up overstates or understates the tax on every line.
This matters because you report and remit the tax portion, and a small per-line error multiplies across an invoice.
Where this saves time
It is built for the quick checks that come up in real billing.
- Verifying a supplier invoice where only the gross total is shown.
- Setting a customer-facing price that lands on a round gross figure after tax.
- Splitting a mixed cart into net and tax for bookkeeping.
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FAQs
What is the difference between GST and VAT here?▼
Mathematically, nothing - both are percentage taxes added on top of a net price, so the same add/remove logic applies. The tool simply lets you enter whatever rate your country uses (for example 5%, 18%, or 20%).
How do I extract the tax from a price that already includes it?▼
Use the 'remove' direction. The tool divides the gross by (1 + rate) to find the net, then the difference is the tax. For 18% on a gross of 118, the net is 100 and the tax is 18.
Can it handle different rates on different items?▼
Calculate each item or rate group separately, then sum the results. A single line uses one rate; mixed-rate invoices are just several of these calculations added together.
Is this valid for filing returns?▼
It is accurate for the arithmetic, but tax filing also involves rules about input credits, place of supply, and rounding conventions specific to your jurisdiction. Use it for line-level checks and confirm filings with official accounting software.
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