Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Total with tax
$108.25
Tax amount
$8.25
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter pre-tax price ($).
- 2Enter tax rate (%).
- 3Read your total with tax on the right — it updates as you type.
- 4Hit Share to keep the scenario or send it to someone.
About this calculator
Compute total price after sales tax, plus the implied tax-free price when working backwards from a total.
Worked example
Using the values the calculator loads with:
Inputs
- Pre-tax price: 100 $
- Tax rate: 8.25 %
Results
- Total with tax: $108.25
- Tax amount: $8.25
What each field means
Inputs
- Pre-tax price ($)
- The pre-tax price used in the calculation, measured in $. Starts at 100 $ so you have a working example on load.
- Tax rate (%)
- The tax rate used in the calculation, measured in %. Starts at 8.25 % so you have a working example on load.
Results
- Total with tax
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Tax amount
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the sales tax calculator work?
Compute total price after sales tax, plus the implied tax-free price when working backwards from a total.
What do I need to enter?
2 values: pre-tax price, and tax rate. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the total with tax result mean?
It is returned as a money amount in US dollars and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
Who is this tool for?
It's built for anyone comparing money scenarios before committing — budgeting a payment, sanity-checking a quote, or seeing what a change in rate or term actually costs.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Sales Tax Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/sales-tax
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/sales-tax" target="_blank" rel="noopener">Sales Tax Calculator — RevenueLab</a> (2026).</p>
Source: [Sales Tax Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/sales-tax) (2026).