Sales Tax and VAT Calculator
Add sales tax or VAT to a net price, or remove it from a tax-inclusive price, at a rate you enter, with quantity totals and the common reverse-tax mistake shown.
Interactive calculator · Method SALES-TAX-VAT-1.0 · Last reviewed: 2026-11-04
Calculate your scenario
Adding tax: tax = net × rate and gross = net × (1 + rate).
Your inputs
Default worked example. Edit the inputs to calculate your scenario.
Default worked example
$100.00 × 8.25% = $8.25 tax; $100.00 × (1 + 0.0825) = $108.25 per unit × 1.
How to use the calculator
Choose whether the price you have excludes tax (add) or already includes it (remove), enter the price per unit, your tax rate and the quantity.
What the result means
Adding 8.25% to $100 gives $8.25 of tax and a $108.25 total; taking 8.25% of $108.25 instead would wrongly suggest $8.93 of tax.
Formula and units
Adding tax: tax = net × rate and gross = net × (1 + rate). Removing tax from a tax-inclusive price: net = gross ÷ (1 + rate) and tax = gross × rate ÷ (1 + rate). Totals multiply by quantity. The mistaken reverse method takes gross × rate, which overstates the tax because the rate applies to the net price, not the gross.
Worked examples
Adding 8.25% sales tax to $100: Price per unit: 100 $; Tax rate (enter your rate; example 8.25%): 8.25 %; Quantity: 1 units; Calculation: add.
Example result: Net total (before tax): $100.00; Tax total: $8.25; Gross total (with tax): $108.25; Per unit: net + tax = gross: $100.00 + $8.25 = $108.25; Mistaken reverse tax (gross × rate): $8.93; Mistake overstates tax by: $0.68.
Removing 20% VAT from three items at 120 each: Price per unit: 120 $; Tax rate (enter your rate; example 8.25%): 20 %; Quantity: 3 units; Calculation: remove.
Example result: Net total (before tax): $300.00; Tax total: $60.00; Gross total (with tax): $360.00; Per unit: net + tax = gross: $100.00 + $20.00 = $120.00; Mistaken reverse tax (gross × rate): $72.00; Mistake overstates tax by: $12.00.
Limitations and common mistakes
Arithmetic only at the rate you enter: no jurisdiction rate lookup, exemptions, compound or stacked taxes, shipping rules, or filing and remittance obligations. Rounding rules (per line, per item or per invoice) vary, so totals may differ by cents from a receipt.
Removing tax by multiplying the tax-inclusive price by the rate: at 20% VAT, £120 × 20% = £24, but the tax inside £120 is only £20.
Sources and assumptions
Method SALES-TAX-VAT-1.0; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.