How to Calculate Sales Tax (Add and Reverse)

Sales tax is a percentage added to a price. Whether you're adding it to a pre-tax amount or working out the tax already baked into a total, it's two short formulas.

Let the tool do it

The Sales Tax Calculator handles both directions — add tax to a price, or remove it from a total — instantly, in your browser.

Adding sales tax to a price

Tax = price × (rate ÷ 100), then total = price + tax.

Example, a $100 item at 8.25%:

• Tax = 100 × 0.0825 = $8.25
• Total = 100 + 8.25 = $108.25

Reversing sales tax out of a total

If you have a tax-inclusive total and want the pre-tax price: price = total ÷ (1 + rate ÷ 100).

Example, a $108.25 total at 8.25%:

• Price = 108.25 ÷ 1.0825 = $100.00
• Tax = 108.25 − 100 = $8.25

Which rate should I use?

Use your combinedlocal rate — state plus any city or county tax. Rates vary a lot by location, so check your area's current rate before relying on a figure.

FAQ

How do I find the tax on a total that already includes it?

Divide the total by (1 + rate as a decimal) to get the pre-tax price, then subtract to get the tax. The calculator's “Remove tax” tab does this.

Is VAT/GST the same?

The math is the same. For VAT/GST specifically, use our GST/VAT Calculator.