Reverse Sales Tax Calculator

Enter the total you paid, including tax, and the sales tax rate. The calculator divides the total by one plus the rate:

• Pre-tax amount: total ÷ (1 + rate ÷ 100)
• Sales tax: total − pre-tax amount

With the defaults, a $107 total at 7% splits into $100 before tax and $7 of tax. This is the figure you need when an expense report asks for the net amount and the tax on separate lines, or when you want to know what an item really cost before tax.

The shortcut most people try is to take 7% of $107 and subtract it. That gives $7.49 of tax and a $99.51 price, which is wrong by 49 cents. The tax was charged on the pre-tax price, not on the total, so the rate has to be divided out rather than subtracted.

The gap grows with the rate. A $100 total at 10% is $90.91 before tax and $9.09 of tax, not $90 and $10. Check any result by multiplying back: $90.91 × 1.10 = $100.

The calculator drops a trailing zero, so $3.30 appears as $3.3.

The last row also works as a budget check. If you can spend $1,250 all in and the rate is 6%, the most you can spend on the price tag is $1,179.25.

Stores round tax to the cent on each sale, so a result can be a cent away from the price on the shelf. That is rounding, not a sign of the wrong rate.

The US has no federal sales tax. Rates are set by states and by local governments, so the right rate depends on where the sale took place, and local rates can apply on top of the state rate. As of January 2026, five states have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire and Oregon. Alaska allows local sales taxes, so a purchase there can still be taxed.

The most reliable rate is the one on the receipt. If it shows only the tax amount, see the FAQ below for working the rate out.

A single rate only works when everything on the receipt was taxed at that rate. Say you bought $60 of taxable goods at 8% plus $15 of untaxed items, for a $79.80 total. Run the whole total through at 8% and the calculator reports $5.91 of tax. The real tax was $4.80.

Instead, back the tax out of the taxed items only: their $64.80 including tax gives $60 and $4.80. Then add the untaxed items back to the pre-tax amount.