How to Calculate Sales Tax
Calculating sales tax is one multiplication, but the rate is where the work is: the rate at the register is the state rate plus the local rate, and it changes from city to city. This page teaches the formula for every direction — adding tax, removing tax and finding the rate — with worked examples you can check by hand, and the sales tax calculator above does the same sums instantly. The basic example: a $100 item in California at 9.03% carries $9.03 of tax and costs $109.03 in total.
The United States has no federal sales tax. Forty-five states levy a statewide sales tax, 38 states let cities and counties add their own, and the average combined rate across the country is 7.53%, according to the Tax Foundation’s midyear 2026 table. The five states with no statewide sales tax are Alaska, Delaware, Montana, New Hampshire and Oregon. Learn the three formulas below and you can work out any sales tax sum with a pocket calculator.
The Sales Tax Formula
The core formula is: tax equals price before tax times the rate divided by 100, and total equals price plus tax. For a $100 item at 9.03%, the tax is $100 times 9.03 divided by 100, which is $9.03, and the total is $100 plus $9.03, which is $109.03. For a $250 item in Texas at 8.20%, the tax is $250 times 8.20 divided by 100, which is $20.50, and the total is $270.50. For a $1,200 laptop in New York at 8.54%, the tax is $1,200 times 8.54 divided by 100, which is $102.48, and the total is $1,302.48.
The other two formulas are the same numbers rearranged. To remove tax from a total, divide the total by one plus the rate: $109.03 divided by 1.0903 is $100.00. To find the rate, divide the tax by the price before tax and multiply by 100: $9.03 divided by $100 times 100 is 9.03%. All three formulas use the same two inputs — a price and a rate — and the calculator above runs all three, plus a receipt mode and a state comparison.
- Add tax. Tax equals price times rate divided by 100. Total equals price plus tax.
- Remove tax. Price before tax equals total divided by one plus the rate.
- Find the rate. Rate equals tax divided by price before tax, times 100.
- Round last. Keep full precision until the end, then round money to the nearest cent.
Step 1 — Find the Right Rate
Look up the average combined rate for the state where the purchase happens. The calculator’s dropdown has all 50 states and DC from the Tax Foundation’s midyear 2026 table: California 9.03%, Louisiana 10.13%, Tennessee 9.61%, Washington 9.57%, Texas 8.20%, New York 8.54%, Florida 6.98%, Oregon 0%. If you know the exact local rate for a city or county, type it in the rate field instead.
Step 2 — Multiply the Price by the Rate
Turn the rate into a decimal by dividing by 100, then multiply by the price. At 9.03%, the decimal is 0.0903. A $49.99 item times 0.0903 is $4.51 of tax. A $500 item times 0.0903 is $45.15 of tax. A $1,000 item times 0.0903 is $90.30 of tax. Add the tax to the price to get the total: $54.50, $545.15 and $1,090.30.
Step 3 — Check the Answer
Check by working backwards: divide the total by one plus the rate and you should get the price back. A $109.03 total divided by 1.0903 is $100.00. If the check fails, the rate is wrong or the rounding went wrong. Round money to two decimal places only at the end of the sum.
Worked Examples: Adding Tax
The table below adds tax to five prices at five different rates, with the arithmetic shown so you can follow each step.
| Price before tax | Rate | Tax | Total |
|---|---|---|---|
| $49.99 | 9.03% (California) | $4.51 | $54.50 |
| $100.00 | 9.03% (California) | $9.03 | $109.03 |
| $250.00 | 8.20% (Texas) | $20.50 | $270.50 |
| $500.00 | 9.61% (Tennessee) | $48.05 | $548.05 |
| $1,200.00 | 8.54% (New York) | $102.48 | $1,302.48 |
Each row is one multiplication and one addition. The $49.99 row shows rounding in action: $49.99 times 0.0903 is $4.514, which rounds to $4.51, and the total is $54.50. The $500 row shows why the combined rate matters: Tennessee’s state rate is 7.00%, but the average combined rate is 9.61%, so the tax is $48.05, not $35.00.
How to Use the Sales Tax Calculator
The calculator above does all three formulas, plus a receipt mode and a state comparison.
- Choose the mode. Add tax is the default. Remove tax, find the rate, receipt and compare are in the same dropdown.
- Pick the state. The rate fills in automatically from the Tax Foundation’s midyear 2026 table.
- Enter the price. The default is $100. For remove-tax mode, enter the total including tax.
- Read the result and the formula. Every result shows the arithmetic underneath, so you can follow it by hand.
- Try the receipt mode for mixed shopping. Enter each item, untick the exempt ones, and the calculator taxes only the ticked items.
What the Calculator Reports
Each mode reports the answer to a different question.
| Mode | Headline result | Formula used |
|---|---|---|
| Add tax | Total including tax | Price times rate, plus price |
| Remove tax | Price before tax | Total divided by one plus the rate |
| Find the rate | Tax rate as a percentage | Tax divided by price, times 100 |
| Receipt | Receipt total including tax | Taxable subtotal times rate, plus subtotal |
| Compare states | Same item in six states | Price times each state’s rate |
Receipt Example: Taxable and Exempt Items Mixed
A receipt with five items shows why the receipt mode matters. The calculator’s defaults are $49.99 taxable, $12.50 exempt, $29.99 taxable, and two items at $0. The subtotal of all items is $92.48, the taxable subtotal is $79.98, the tax at 9.03% is $7.22 and the total is $99.70. If the whole receipt had been taxed, the tax would have been $8.35, so unticking the exempt item saves $1.13 on this small shop.
Common Mistakes When Calculating Sales Tax
These are the errors that show up again and again.
- Using the state rate instead of the combined rate. California’s 7.25% state rate gives $7.25 of tax on $100, but the checkout rate averages 9.03%, so the real tax is $9.03.
- Subtracting the rate to remove tax. Taking 9.03% off $109.03 gives $99.22, not $100.00. Divide by 1.0903 instead.
- Rounding too early. Round to the cent only at the end. Rounding the rate to 9% first gives $1,000.28 instead of $1,000.00 when reversing a $1,090.30 total.
- Taxing exempt items. Groceries are exempt in most states and prescription drugs almost everywhere except Illinois, which charges 1% on drugs.
- Using a stale rate. Louisiana’s state rate rose to 5% in 2025. Many pages still show the old 4.45%, which understates the tax by $0.55 on every $100.
Tips for Calculating Sales Tax by Hand
Five habits that keep hand calculations right.
- Write the rate as a decimal first. 9.03% becomes 0.0903. Multiplying by the decimal is one step, and it stops the common error of multiplying by 9.03 and forgetting to divide by 100.
- Estimate before you calculate. Ten percent of $100 is $10, so 9.03% must be a little less than $10. If your answer is far from the estimate, check the rate.
- Check by reversing. Divide the total by one plus the rate and confirm you get the price back.
- Keep the receipt. It shows the total and the state, which are the two inputs for removing tax later.
- Use the combined rate. The rate at the register is state plus local. The calculator’s dropdown uses the average combined rate for each state.
Sales Tax Formula Quick Answers
The three formulas in one place, with the default example for each.
| What you want | Formula | Example (California, 9.03%) |
|---|---|---|
| Tax on a price | Price times rate divided by 100 | $100 times 9.03% = $9.03 |
| Total including tax | Price plus tax | $100 + $9.03 = $109.03 |
| Price before tax | Total divided by one plus the rate | $109.03 / 1.0903 = $100.00 |
| Tax rate | Tax divided by price, times 100 | $9.03 / $100 x 100 = 9.03% |
| Tax on $500 | $500 times 9.03% | $45.15, total $545.15 |
| Tax on $1,000 | $1,000 times 9.03% | $90.30, total $1,090.30 |
Related tools on this site: the main sales tax calculator, the discount calculator for sale prices, and the percentage calculator for any other percentage sum. The rates come from the Tax Foundation’s 2026 sales tax rates, midyear update.
Frequently Asked Questions
What is the formula for sales tax?
Tax equals price before tax times the rate divided by 100, and the total equals price plus tax. For a $100 item at 9.03%, the tax is $100 times 9.03 divided by 100, which is $9.03, and the total is $109.03.
How do I calculate sales tax on $250?
Multiply $250 by the rate as a decimal. In Texas at 8.20%, that is $250 times 0.082, which is $20.50 of tax and a $270.50 total. In California at 9.03%, it is $250 times 0.0903, which is $22.58 of tax and a $272.58 total.
How do I calculate sales tax backwards?
Divide the total by one plus the rate. A $109.03 total at 9.03% gives $109.03 divided by 1.0903, which is $100.00 before tax, so the tax paid was $9.03. Use the remove-tax mode in the calculator above.
How do I calculate the sales tax rate from two prices?
Subtract the price before tax from the total to get the tax, then divide the tax by the price before tax and multiply by 100. A $100 price and a $109.03 total give $9.03 of tax, and $9.03 divided by $100 times 100 is 9.03%.
How do I calculate sales tax on a receipt with several items?
Add up the taxable items only, then multiply that subtotal by the rate. In the calculator’s receipt mode, the defaults give a $92.48 subtotal with $79.98 of taxable items, $7.22 of tax at 9.03% and a $99.70 total. Untick groceries and other exempt items before you calculate.
Disclaimer: This calculator is for general information only and is not tax advice. Rates are averages from the Tax Foundation’s midyear 2026 table; your exact rate depends on the county and city. Verify the rate with your local jurisdiction before using it for business or tax filing.