Sales Tax Calculator
Figure out the tax either direction: add your local rate to a price, or find how much tax sits inside a total you already paid.
Last updated: August 5, 2026
How sales tax is applied
Sales tax is a percentage of the purchase price added at the till. In most of the US, that rate is actually a stack of separate rates — state, county, city — that add up to the number on your receipt, which is why 8.75% appears where you expected 6%.
The tool does two things. In its first mode you give it a price before tax and it adds your rate. In the second, you give it the price you actually paid and it works backwards, pulling the tax out of the total.
Which you need depends on the question. Budgeting for a purchase, you need mode one. Checking how much a government collected from your last transaction for a dispute, you need mode two. The rate field is the same both ways.
The formulas
Worked example
Adding 8.25% tax to a $120 item: tax = $9.90, total = $129.90.
Reverse: if you paid $129.90 with the same rate, the pre-tax price was $120.00 and the tax was $9.90.
The second direction is the one people get wrong, because you cannot simply multiply by 0.0825 — the tax is 8.25% of the pre-tax price, not of the total.
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Frequently asked questions
Why does the total not equal pre-tax times rate plus 1?
It does, once rounding is ignored. Rounding to the nearest cent on the tax can make the two-digit ends differ by a cent in either direction. That is normal, not a mistake.
Are online purchases taxed?
In most places, yes, since many online sellers now collect tax for the buyer's location rather than the seller's. Your shopping total will usually show it, as the local rules apply.
Does shipping get taxed?
Often, but not always. Some states tax the shipping when the goods are taxable, others exempt it. Enter the shipping in the price if it was taxed in your area.