Everyday desk
Sales Tax Calculator
Calculate tax and total from a subtotal and tax rate.
Sales Tax Calculator: Add a tax amount to a price before tax using a percentage you supply. This page shows the tax and the resulting total; it does not determine a local rate or extract tax already included in a displayed price. Runs 100% locally in your browser with zero server file uploads.
- Category
- Calculators
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Total with tax
$108.50
- Tax amount
- $8.50
Tax = subtotal × tax rate ÷ 100; total = subtotal + tax- This is a simple planning estimate. Enter monetary values in one currency; no exchange-rate conversion is performed.
- Calculations run locally in your browser and do not account for jurisdiction-specific taxes, fees, benefits, or contract terms unless you enter them.
Formula and worked example
Tax = subtotal × tax rate ÷ 100; total = subtotal + tax
A worked example with sample values:
| Inputs | |
|---|---|
| Subtotal | $100.00 |
| Tax rate | 8.5% |
| Results | |
|---|---|
| Total with tax | $108.50 |
| Tax amount | $8.50 |
Tax added to a subtotal
Tax = before-tax subtotal × tax percentage ÷ 100. Total with tax = subtotal + tax. Using the widget's illustrative subtotal of 100 and sample rate of 8.5%, tax is 100 × 8.5 ÷ 100 = 8.50 and the total is 100 + 8.50 = 108.50. This example is not a rate recommendation for any location.
OpenStax explains tax as a percentage added to the purchase price (https://openstax.org/books/contemporary-mathematics/pages/6-2-discounts-markups-and-sales-tax). A positive subtotal is required; entering a zero tax percentage leaves the subtotal unchanged. Money outputs are formatted for display without deciding invoice rounding rules.
Included tax and local treatment
For an inclusive total T and tax percentage r, before-tax price = T ÷ (1 + r ÷ 100), and included tax = T − before-tax price. For the same illustrative total of 108.50 and rate of 8.5%, dividing by 1.085 recovers 100 before tax and 8.50 included tax. Multiplying an inclusive total by the tax rate would overstate the embedded tax.
California's tax authority explains that rates depend on location (https://aws.cdtfa.ca.gov/taxes-and-fees/know-your-rate.htm). Consult the relevant authority for the transaction you are pricing. This calculator supplies arithmetic for an entered rate; discounts, shipping, exemptions and multiple tax layers need the correct taxable base and treatment before you use that arithmetic.
How to use it
- Enter values using the units and assumptions shown beside each field.
- Calculate the fixed formula locally in your browser.
- Review the estimate and copy the result when useful.
Privacy & limitations
Values stay on this device. These are simple planning estimates, not tax, legal, employment, rental, accounting, or financial advice; verify material decisions against your local rules and source documents.
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Frequently asked questions
Does this add sales tax or remove included tax?
It adds tax to the entered subtotal. If your price already includes tax, first divide that total by 1 + rate ÷ 100 to find the before-tax amount. Entering the tax-inclusive total as Subtotal would add the tax again.
Which sales-tax rate should I enter?
Use the applicable rate for the location and transaction. Rates vary by place, and tax treatment can depend on what is sold. The default is a sample input rather than a verified local rate; this tool has no address lookup, exemption checker or rate database.
Can I use one rate for a basket with exempt items?
Apply the rate to the taxable subtotal, rather than the whole basket, and add exempt amounts afterwards. For items taxed at different rates, calculate their groups separately. The widget accepts only one subtotal and one rate, so it cannot allocate a mixed basket automatically.
Embed this tool
Free to use on any website. Paste the code where the tool should appear; the link under it lets readers open the full page.
<iframe src="https://toea.com/embed/sales-tax-calculator" title="Sales Tax Calculator" width="100%" height="820" style="border:0;max-width:680px" loading="lazy"></iframe>
<p style="margin:4px 0 16px;font-size:13px"><a href="https://toea.com/sales-tax-calculator">Sales Tax Calculator</a> · TOEA</p>
<script>addEventListener("message",function(e){if(e.origin!=="https://toea.com"||!e.data||e.data.type!=="toea-embed-height")return;document.querySelectorAll("iframe").forEach(function(f){if(f.contentWindow===e.source)f.style.height=e.data.height+"px"})})</script>Free tool · runs in your browser · no account required