How VAT & Tax Calculator works
The VAT and sales tax calculator works in both directions: enter a net price and a tax rate to get the gross total, or paste a tax-inclusive gross amount to recover the pre-tax net and the exact tax charged. Common rates (5, 10, 15, 20, 21, 25 percent) are one-tap presets, and any custom rate is accepted.
The same arithmetic covers VAT, GST, HST and US sales tax, only the rate changes, and the remove-tax mode back-calculates the net with net = gross / (1 + rate/100) so you can see exactly how much tax a quoted price already includes.