Sales Tax Calculator

How sales tax is added — and removed

Adding sales tax is straightforward: multiply the pre-tax price by the tax rate and add it back. The more common mistake is working backwards. If you have a receipt total that already includes tax and want the pre-tax amount, you cannot just subtract the rate — you divide by one plus the rate. At an 8% rate, a $108 total came from a $100 item ($108 ÷ 1.08), not $99.36.

In the United States there is no national sales tax. The rate you pay is a state base rate plus, in most states, additional city, county, and special-district taxes stacked on top — so the combined rate at the register is often one to four percentage points above the state figure. Five states (Alaska, Delaware, Montana, New Hampshire, Oregon) have no statewide sales tax, though some Alaska localities levy their own.

What gets taxed also varies. Many states exempt groceries and prescription drugs, tax prepared food at a higher rate, and treat clothing or digital goods differently. For an exact figure on a specific purchase, use your state or local revenue department’s rate lookup by address.

For business use, remember that sales tax you collect is not revenue — it is money held on behalf of the tax authority and remitted on a schedule. The reverse ("extract") mode here is useful for backing tax out of gross receipts when you record income separately from the tax collected.

Add tax:  tax = price × rate ;  total = price + tax
Remove tax:  pre-tax = total ÷ (1 + rate) ;  tax = total − pre-tax
(rate as a decimal, e.g. 7.25% → 0.0725)