Sales Tax

Adding or Removing Sales Tax from a Price

Sales tax is calculated by multiplying a price by the local tax rate, then adding that amount to the price to get the final total. Enter a price and a sales tax rate, and this calculator handles two everyday questions:

• Add tax to a price — you know the price before tax and want to know the final total (and how much of it is tax).
• Find the price before tax — you’re looking at a receipt or invoice that already includes tax, and want to work backward to the original price and the tax amount.

Sales tax rates vary by state, county, and city, and change over time — this calculator doesn’t guess at a specific rate for you. Enter whatever rate applies where you’re shopping (check your receipt, your state/local revenue department, or a point-of-sale system for the exact rate).

The Formula

Every quantity is color-coded and carried through consistently:

$$\text{Adding tax: } \vC{\text{Tax Amount}} = \vA{\text{Price}} \times \left(\frac{\vB{\text{Rate}}}{100}\right)$$ $$\vD{\text{Total}} = \vA{\text{Price}} + \vC{\text{Tax Amount}}$$

Finding the price before tax rearranges that same relationship backward:

$$\vD{\text{Total}} = \vA{\text{Price}} \times \left(1 + \frac{\vB{\text{Rate}}}{100}\right) \quad\Rightarrow\quad \vA{\text{Price}} = \frac{\vD{\text{Total}}}{1 + (\vB{\text{Rate}} \div 100)}$$

Worked Example

Adding tax: An $80 item at a 7.25% sales tax rate:

1. Tax Amount: $\vA{80} \times \vB{0.0725} = \vC{5.80}$ dollars.
2. Total: $\vA{80} + \vC{5.80} = \vD{85.80}$ dollars.

Finding the price before tax: A receipt shows an $85.80 total at 7.25% tax:

1. Price: $\vD{85.80} \div 1.0725 \approx \vA{80.00}$ dollars.
2. Tax Amount: $\vD{85.80} - \vA{80.00} = \vC{5.80}$ dollars.

Both directions agree, as they should — adding tax to $80 gives $85.80, and working backward from $85.80 gives $80 again.

Key Factors to Consider

• Combined sales tax rates are usually made up of several layers stacked together. A state-level rate, plus a county rate, plus sometimes a city or special-district rate, all add up to the single combined percentage charged at checkout — a receipt’s rate reflects all of those layers already summed, which is exactly the figure this calculator expects.
• Online purchases are generally taxed based on the buyer’s shipping address, not the seller’s location. Since a 2018 U.S. Supreme Court ruling (South Dakota v. Wayfair), most states require online retailers to collect sales tax based on where a purchase is delivered, even if the retailer has no physical presence there — this is why the same online item can show a different tax amount depending on the shipping address entered at checkout.
• A handful of states charge no state-level sales tax at all. Alaska, Delaware, Montana, New Hampshire, and Oregon don’t levy a statewide sales tax (though some allow local jurisdictions to add their own) — always check the specific rate for wherever a purchase is actually happening rather than assuming a rate applies universally.
• “Use tax” is the lesser-known counterpart to sales tax, owed when sales tax wasn’t collected at the time of purchase. Many states legally require buyers to self-report and pay an equivalent use tax on out-of-state or online purchases where sales tax wasn’t charged — this is a genuine legal obligation in many places, even though it’s widely under-reported in practice.

Common Mistakes

• Assuming one rate applies everywhere. Sales tax varies by state, county, and even city — five states charge no state sales tax at all — so the rate used here should be your own local combined rate, not a national average.
• Applying tax to exempt items. Groceries, prescription medication, and clothing are tax-exempt or taxed at a reduced rate in many states — check your local rules before assuming every purchase is taxed the same way.
• Mixing up the two modes. Adding tax to a pre-tax price and working backward from a tax- included total are the reverse of each other — using the wrong mode for the number you actually have gives a technically-correct but mismatched answer.

Useful to Know

• Want to figure out the price after a store discount, tax included? Discount Calculator applies a percentage discount, which you can then run through this calculator’s “Add tax to a price” mode.
• Trying to work out a markup or profit margin instead of a tax rate? Margin Calculator handles that calculation directly.
• Curious how a percentage change like a tax rate relates to other percentage math? Percentage Calculator covers percentage increase, decrease, and of-a-number calculations more generally.