Formulas and sources
Each formula this calculator uses, where it comes from, and what it leaves out. "How it works" shows the same formula with your own numbers.
Total with tax
Add Tax mode
- Total
- the price with sales tax added
- Price
- the price before tax
- Rate
- the sales tax rate, in percent: the state rate plus any county, city or district rate
The tax is rounded to the nearest cent before it is added (see Rounding to the cent).
Source: Standard formula; no single publisher. The Oklahoma Tax Commission's and the Utah State Tax Commission's worked examples give the same tax and total [1] [2].
Price before tax
Remove Tax mode
- Net Price
- the price before tax
- Total
- the amount paid, tax included
- Rate
- the sales tax rate, in percent
The price is rounded to the nearest cent and the tax is the total minus it. A price worked back from a receipt can miss the shelf price by a cent, because the receipt's tax was rounded too.
Source: Uses the method in the Utah State Tax Commission's Publication 25 for tax-included vending machine prices: divide by one plus the rate [2].
Rounding to the cent
Every mode
Half up: a tax of $0.175 becomes $0.18, so $2.80 at 6.25% gives $0.18 tax and a $2.98 total.
Source: Streamlined Sales and Use Tax Agreement, Section 324 [3]: it requires this rule of its member states, rounding up to the next cent when the third decimal place is greater than four. Other states set their own rules.
Preset rates
Every mode
Hawaii's 4% is a general excise tax on the business.
Source: Each state's own page or statute, linked under Preset Rates for the selected state and checked on October 5, 2026, except Utah's fourth-quarter rate chart, which could not be read. The local parts: California's tax agency [4], Nevada's statute [5], Virginia's statute and tax department [6] [7], and Utah's Publication 25 and rate charts [2] [8]. Hawaii: its Department of Taxation [9].
Sources
- Oklahoma Tax Commission. Sales and Use Tax, cash rounding, Example One and Example Two. Web page, no date shown; read October 5, 2026.
- Utah State Tax Commission. Publication 25: Sales and Use Tax General Information, Example of Tax Calculation with City-Imposed Tax; Vending Machine Sales; Chart 2, Taxes in the Combined Rate. Rev. 08/26, draft pending public meeting as of September 30, 2026; same example, method and chart as Rev. 02/26.
- Streamlined Sales Tax Governing Board. Streamlined Sales and Use Tax Agreement, Section 324: Rounding Rule. As amended through December 19, 2025.
- California Department of Tax and Fee Administration. Detailed Description of the Sales & Use Tax Rate, the components of the statewide 7.25% rate, including 1.25% local. Web page, no date shown; read October 5, 2026.
- Nevada Legislature. Nevada Revised Statutes, Chapter 377: City-County Relief Tax, NRS 377.030(1) and 377.040(1). Rev. 6/29/2024.
- Virginia General Assembly. Code of Virginia, Title 58.1, Chapter 6: Retail Sales and Use Tax, § 58.1-603 and § 58.1-605(B). Text read October 5, 2026.
- Virginia Tax. Retail Sales and Use Tax, the rate table, "5.3% Everywhere else". Web page, no date shown; read October 5, 2026.
- Utah State Tax Commission. Sales & Use Tax Rates, combined rate charts, lowest rate. Rates in effect January 1, April 1 and July 1, 2026.
- Hawaii Department of Taxation. General Excise Tax (GET): Frequently Asked Questions, the 4% rate, the county surcharge and the maximum pass-on rate. Web page, no date shown; read October 5, 2026.
What this calculator does not cover
- It applies one rate to one amount. County, city and district rates are not in the presets, apart from the statewide local parts above, and they differ by address.
- It does not know which items a state exempts or taxes at a lower rate, such as groceries, clothing, prescription drugs or services.
- It does not decide where a sale is taxed.
- It leaves out use tax, tax holidays, shipping charges and taxes that are not a retail sales tax, such as Arizona's transaction privilege tax and New Mexico's gross receipts tax. Hawaii is the one such tax with a preset: its 4% is the general excise tax at the state rate, without the county surcharge or the higher rate a business may pass on to the buyer [9].
- It shows the tax and total before any cash rounding. Where a store rounds a cash total to the nearest nickel, the tax is still worked out on the price before that rounding.
Sources checked on .