Sales Tax & VAT Calculator — Add or Remove Tax
Enter a price and a tax rate, then choose whether to add tax to a pre-tax amount or strip it out of a tax-inclusive total. CalcWize shows the net (pre-tax) amount, the tax itself, and the gross total. Use it to build an invoice, check a receipt, or work out the tax-exclusive price behind a shelf tag.
Adding tax
To add tax, multiply the net price by one plus the rate over 100. $100 at 8.5% becomes $100 × 1.085 = $108.50, of which $8.50 is tax. This is what you do when quoting a price before tax is applied.
Removing tax
To strip tax from an inclusive total, divide by one plus the rate — don’t just subtract the percentage. $108.50 ÷ 1.085 = $100 net, not $108.50 − 8.5%, which would be wrong. The calculator does this correctly in “remove” mode.
Sales tax vs VAT
Sales tax is usually added at the till and shown separately; VAT and GST are typically baked into the displayed price. The maths is identical — what differs is whether the figure you start with already includes the tax.
Common mistakes
Subtracting the percentage to remove tax (it overshoots); applying the rate twice; and mixing inclusive and exclusive prices in the same total.
Frequently asked questions
- How do I remove tax from a total?
- Divide by one plus the rate, don’t subtract the percentage. $108.50 at 8.5% included is 108.50 ÷ 1.085 = $100 net. Subtracting 8.5% would wrongly give $99.27, because the percentage applied to the larger gross figure.
- Is VAT calculated the same way as sales tax?
- The arithmetic is identical. The practical difference is that VAT/GST is usually shown tax-inclusive on the shelf, while US sales tax is added at the register — so you’ll more often “remove” VAT and “add” sales tax.
- What if different items have different rates?
- This tool applies one rate to the whole amount. For a receipt mixing rates (say food at one rate and other goods at another), calculate each group separately and add the results.
How we calculate it
Add mode: total = net × (1 + rate ÷ 100), and tax = total − net. Remove mode: net = total ÷ (1 + rate ÷ 100), and tax = total − net. Dividing — not subtracting the percentage — is what correctly strips tax out of an inclusive price.
What it doesn't do
- Multiple or tiered tax rates on one receipt
- Tax exemptions, thresholds, or reverse-charge rules
- Filing or remittance — this is a price calculator, not tax advice
Last reviewed: 2026-05