Answer first
What this calculator tells you
Find the price before tax and the tax amount from a total that already includes sales tax. Back the tax out of a receipt to see what the item cost. Formula: Price before tax = total ÷ (1 + tax rate); tax = total − price before tax. At the worked-example inputs, the price before tax is $100. Holding every other input steady, moving sales tax rate from 5.3% to 9.3% moves the result from $98 to $102.
Transparent method
The formula
Back the tax out of a receipt to see what the item cost.
Worked example
Example inputs
How to interpret the result
Tax is added on top of the price, so it cannot be backed out by subtracting the rate from the total. It has to be divided out. A $107.25 receipt at 7.25 percent came from a $100.00 price plus $7.25 of tax. Taking 7.25 percent of the total instead gives $7.78 and a price of $99.47, which is wrong by more than 50 cents, and the error grows on bigger purchases.
At the worked-example inputs the price before tax is $100. It rises with total paid including tax and falls as sales tax rate increases.
This is a simplified educational estimate, not a tax return.
Before you rely on it
What to check
Confirm the rate that applied at the register. State, county and city rates stack, and some items are taxed at a different rate or not at all.
The common error
Where people go wrong with reverse sales tax calculator
Multiplying the total by the tax rate to find the tax. The rate applies to the pre-tax price, so it must be divided out of the total.
Sensitivity evidence
How sales tax rate changes the price before tax
Holding every other input at the worked-example value, moving sales tax rate from 5.3% to 9.3% moves the price before tax from $98 to $102: a spread of $3.73, or 4% of the worked-example result.
| Sales tax rate | Price before tax | Tax included in the total |
|---|---|---|
| 5.3% | $102 | $5.35 |
| 6.3% | $101 | $6.31 |
| 7.3%worked example | $100 | $7.25 |
| 8.3% | $99 | $8.17 |
| 9.3% | $98 | $9.08 |
Every input, tested
Which input moves the price before tax most
Of the 2 inputs, total paid including tax moves the price before tax most ($20 across the range tested) and sales tax rate moves it least ($1.86).
| Input | Tested from | To | Price before tax at each end | Swing |
|---|---|---|---|---|
| Total paid including tax | $97 | $118 | $90 to $110 | $20 (20%) |
| Sales tax rate | 6.3% | 8.3% | $101 to $99 | $1.86 (1.9%) |
Two variables at once
Price before tax by sales tax rate and total paid including tax
Across the grid the price before tax runs from $79 to $123. Moving sales tax rate from 5.3% to 9.3% shifts it by $3.72 at the middle column, and moving total paid including tax from $86 to $129 shifts it by $40 at the middle row, so total paid including tax is the bigger lever here.
| Sales tax rate \ Total paid including tax | $86 | $107 | $129 |
|---|---|---|---|
| 5.3% | $82 | $102 | $123 |
| 6.3% | $81 | $101 | $121 |
| 7.3% | $80 | $100 | $120 |
| 8.3% | $79 | $99 | $119 |
| 9.3% | $79 | $98 | $118 |
The highlighted cell is the worked example.
Step by step
The worked example, input by input
| Input | Value used | What it means |
|---|---|---|
| Total paid including tax | $107 | Enter the total paid including tax used in this calculation. |
| Sales tax rate | 7.3% | Enter the sales tax rate used in this calculation. |
| Price before tax | $100 | |
| Tax included in the total | $7.25 | |
Inputs, definitions and assumptions
Total paid including tax
Enter the total paid including tax used in this calculation. The prefilled worked-example value is $107.
Sales tax rate
Enter the sales tax rate used in this calculation. The prefilled worked-example value is 7.3%.
How to use this calculator
- 1Verify the inputs. Gather total paid including tax and sales tax rate from your own documents; the prefilled values are examples.
- 2Save a baseline. The worked example puts the price before tax at $100. Store your own version of it as Scenario A.
- 3Test one change. Start with total paid including tax, the input with the biggest effect here: moving total paid including tax from $97 to $118 takes the price before tax from $90 to $110, a swing of 20% of the worked-example figure.
- 4Check the extremes. At half the example total paid including tax ($54) the price before tax is $50; at double ($215) it is $200.
People also ask
Frequently asked questions
How do you calculate reverse sales tax?
Price before tax = total ÷ (1 + tax rate); tax = total − price before tax. Enter total paid including tax in dollars and sales tax rate in percent (7.25 means 7.25%). At the worked-example inputs the price before tax is $100.
What does the reverse sales tax result mean?
Back the tax out of a receipt to see what the item cost. At the worked-example inputs the price before tax is $100. It rises with total paid including tax and falls as sales tax rate increases.
How much does sales tax rate change the price before tax?
Holding every other input at the worked-example value, moving sales tax rate from 5.3% to 9.3% moves the price before tax from $98 to $102, a spread of $3.73.
What are the limits of this reverse sales tax calculator?
This is a simplified educational estimate, not a tax return. The tables on this page test sales tax rate only from 5.3% to 9.3%; a value outside that range is not tabulated here.
Which input moves the price before tax most in the reverse sales tax calculator?
Ranked by how far each moves the price before tax across the range tested: total paid including tax ($20, 20%) and sales tax rate ($1.86, 1.9%).
If I double total paid including tax in the reverse sales tax calculator, does the price before tax double?
Doubling it from $107 to $215 takes the price before tax from $100 to $200, which is 2.00 times the worked-example figure. So the result scales almost exactly in proportion. Halving it to $54 gives $50.
How much does total paid including tax matter in the reverse sales tax calculator?
The worked example uses $107. Holding every other input at its worked-example value, moving total paid including tax from $97 to $118 takes the price before tax from $90 to $110, a swing of 20% of the worked-example figure.
Which inputs change the tax included in the total in the reverse sales tax calculator?
At the worked-example inputs it is $7.25. Total paid including tax takes it from $6.56 to $7.98 and sales tax rate takes it from $6.31 to $8.17.
What is the difference between a tax deduction and a tax credit?
A deduction reduces taxable income. So it saves tax equal to its amount times your marginal rate. A credit reduces the tax bill directly. A credit is therefore worth more than an equally sized deduction for anyone below the top rate. Some are refundable while others are not.
Sources and evidence
Free Calculators Online is independent and is not affiliated with or endorsed by the source organizations. Educational estimates only.