Reverse sales tax calculator
Take the tax back out of a total.
Use the combined rate: state plus county, city and any special district. It depends on the address of the sale, so check it with your state's department of revenue.
Formula: price before tax = total ÷ (1 + rate). Results are rounded to the cent, so a receipt can differ by a cent where the seller rounded each line separately. Nothing you type here leaves your browser.
To find the price before tax, divide the total by one plus the tax rate as a decimal. At a combined rate of 8.25%, a total of $108.25 divided by 1.0825 gives $100.00 before tax and $8.25 of tax. Subtracting 8.25% of the total gives the wrong answer, because the tax was charged on the price, not on the total.
How the reverse calculation works
Sales tax is added on top of the price: total = price × (1 + rate). Working backwards means undoing that multiplication, so the price before tax is the total divided by (1 + rate), and the tax is whatever is left.
| Total paid | Combined rate | Divide by | Price before tax | Tax included |
|---|---|---|---|---|
| $108.25 | 8.25% | 1.0825 | $100.00 | $8.25 |
| $50.00 | 6% | 1.06 | $47.17 | $2.83 |
| $1,000.00 | 7.5% | 1.075 | $930.23 | $69.77 |
The calculator also runs the other way: give it the total and the price before tax, and it returns the rate that was actually charged. That is the quick check when a receipt looks wrong.
Why you cannot just subtract the rate
The common mistake is to take 8.25% of $108.25 and subtract it. That gives $8.93 of tax and a price of $99.32, which is 68 cents out on a single receipt. The error grows with the amount and the rate, and across a year of expenses it stops being rounding.
The reason is that the percentage was applied to the price, which is smaller than the total. Taking the same percentage of the total always overstates the tax.
When you need it
Expense reports and bookkeeping. Most receipts show a total, and accounting needs the net amount and the tax separately.
Tax-inclusive pricing. If you sell at markets, events or anywhere a round number on the sign matters, you set the total you want the customer to pay and work back to the price you record and the tax you owe.
Checking a charge. If the total does not match the rate you expected, the rate mode tells you what was actually applied.
Finding the right rate
Use the combined rate for the place of sale: the state rate plus any county, city and special district rates. Two addresses in the same state can have different rates, so the state’s department of revenue is the place to confirm it.
Five states have no statewide sales tax: Alaska, Delaware, Montana, New Hampshire and Oregon. Alaska still allows local sales taxes, and more than 100 of its municipalities or boroughs levy one.
Source: Avalara, States with no sales tax, reviewed March 2026.
FAQ
How do I calculate sales tax backwards from a total? Divide the total by one plus the rate as a decimal. The result is the price before tax, and the difference between the two is the tax.
What is the formula for the price before tax? Price before tax = total ÷ (1 + rate). At 8.25%, divide by 1.0825; at 6%, divide by 1.06.
Why is subtracting the tax percentage from the total wrong? The tax was calculated on the price, which is smaller than the total. Taking the percentage of the total overstates the tax every time.
How do I find the sales tax rate from a receipt? Divide the total by the price before tax and subtract one. Multiply by 100 to read it as a percentage, or use the rate mode in the calculator.
Which sales tax rate should I use? The combined rate for the address of the sale: state plus local rates. Confirm it with the state’s department of revenue, since rates differ within the same state.
More calculators: Free Tools