The U.S. has no federal sales tax — every rate is set by a state, county, or city, and rates vary widely by location, so this calculator takes the rate as an input rather than assuming one.
How it works
Going forward, tax is the pre-tax price times the rate, added on top. Going backward from a tax-inclusive total — like a receipt total — the pre-tax price is the total divided by (1 + rate), not the total with the rate simply subtracted, since the rate was applied to the smaller pre-tax price in the first place.
How to use this calculator
- Choose whether you’re entering a pre-tax price or a tax-inclusive total.
- Enter the amount and the local sales tax rate.
A worked example
A jacket is priced at $89.99 and the combined local sales tax rate is 8.25%.
Tax is 89.99 × 0.0825 = $7.42, so the total at the register is 89.99 + 7.42 = $97.41.
Now run it backwards. Starting from that $97.41 receipt total, the pre-tax price is 97.41 ÷ 1.0825 = $89.99 — back where we started. The tempting shortcut, subtracting 8.25% from the total, gives 97.41 × 0.9175 = $89.37, which is 62 cents too low. That gap is the whole reason the reverse calculation divides instead of subtracting.
What the variables mean
| Variable | Meaning | In the example |
|---|---|---|
| Pre-tax price | The listed price before any sales tax is applied | $89.99 |
| Rate | Combined state, county and city rate, as a percentage | 8.25% |
| Tax amount | Pre-tax price × rate | $7.42 |
| Total | Pre-tax price + tax amount | $97.41 |
Edge cases worth knowing
Rounding is applied per transaction, not per item. Tax on a multi-item receipt is normally computed on the taxable subtotal and rounded once, so adding up separately-rounded per-item tax can differ by a cent or two from the register total.
A 0% rate is a valid answer, not an error. Several U.S. states levy no statewide sales tax at all, so entering 0 is legitimate and returns a total equal to the pre-tax price.
The rate is not always the rate at the store. For delivered goods, many jurisdictions apply the rate at the destination address rather than the seller’s location, so the correct rate to enter may not be the one where the purchase was made.
Frequently asked questions
Why can’t I just subtract the tax rate from a total to get the pre-tax price?
Because the rate was applied to the pre-tax price, a smaller number — subtracting a percentage of the larger total overstates how much tax was actually included.
Where do I find my local sales tax rate?
State and local revenue department websites publish current rates by jurisdiction; combined state, county, and city rates can differ meaningfully within the same state.
Does this handle tax-exempt items?
No — it assumes the full amount is taxable. Many jurisdictions exempt categories like groceries or medication, which this calculator doesn’t distinguish.
