Free Embeddable Wheel and Tire Calculators

Give your readers a working calculator instead of a paragraph of formulas. Each calculator below is free to put on your own site with two lines of HTML: no ads, no affiliate links, no cookies, no sign-up. The only condition is the small “Calculator by CheckFitment” credit line that comes with it.

How it works

Pick a calculator below and copy its two-line snippet.
Paste it into your page where the calculator should appear (most editors have an “HTML” or “custom code” block).
That is all. The calculator takes its colors from your page, so it fits a light or a dark theme, and it fits down to a 320 px wide phone. The maths is the same as on checkfitment.com, so a fix here fixes every embed.

Terms. Free for any website, including commercial ones. Keep the “Calculator by CheckFitment” credit link visible next to the calculator. No reselling, no repackaging as your own product or app, and no hosting your own copy of the script: load it from checkfitment.com so corrections reach you. The calculators are reference tools, not an engineering approval or safety inspection, and come without warranty. We may improve or retire a calculator; the snippet keeps working while it exists.

Privacy

The script sets no cookies and stores nothing in the visitor's browser. Besides the script itself it makes one request to checkfitment.com when your page loads, carrying only your site's domain name and which calculators the page uses. Nothing a visitor types into a calculator leaves their browser.

Wheel offset calculator

Old wheel vs new wheel: how far the outer edge pokes, how far the inner edge moves, backspacing.

Snippet

<div data-checkfitment="wheel-offset"></div>
<script async src="https://checkfitment.com/embed.js"></script>

Iframe version, if your site does not allow scripts

An iframe works anywhere, but a link inside an iframe does not count as a link on your page, so the credit line sits outside it in this version. Please keep it.

<iframe src="https://checkfitment.com/embed/frame/?w=wheel-offset" title="Wheel offset calculator" width="100%" height="460" style="border:0;max-width:640px" loading="lazy"></iframe>
<p><a href="https://checkfitment.com/wheel-offset-calculator/">Calculator by CheckFitment</a></p>

Open the full wheel offset calculator page →

Backspacing and offset converter

Backspacing in inches to offset in mm, and back, for any wheel width.

Snippet

<div data-checkfitment="backspacing"></div>
<script async src="https://checkfitment.com/embed.js"></script>

Iframe version, if your site does not allow scripts

An iframe works anywhere, but a link inside an iframe does not count as a link on your page, so the credit line sits outside it in this version. Please keep it.

<iframe src="https://checkfitment.com/embed/frame/?w=backspacing" title="Backspacing and offset converter" width="100%" height="340" style="border:0;max-width:640px" loading="lazy"></iframe>
<p><a href="https://checkfitment.com/backspacing-calculator/">Calculator by CheckFitment</a></p>

Open the full backspacing and offset converter page →

Bolt pattern converter

Wheel bolt pattern between mm and inches for 4, 5, 6 or 8 lugs.

Snippet

<div data-checkfitment="bolt-pattern"></div>
<script async src="https://checkfitment.com/embed.js"></script>

Iframe version, if your site does not allow scripts

An iframe works anywhere, but a link inside an iframe does not count as a link on your page, so the credit line sits outside it in this version. Please keep it.

<iframe src="https://checkfitment.com/embed/frame/?w=bolt-pattern" title="Bolt pattern converter" width="100%" height="300" style="border:0;max-width:640px" loading="lazy"></iframe>
<p><a href="https://checkfitment.com/bolt-pattern-converter/">Calculator by CheckFitment</a></p>

Open the full bolt pattern converter page →

Wheel spacer calculator

Effective offset and spacer size, plus the stud-engagement check for slip-on spacers.

Snippet

<div data-checkfitment="wheel-spacer"></div>
<script async src="https://checkfitment.com/embed.js"></script>

Iframe version, if your site does not allow scripts

An iframe works anywhere, but a link inside an iframe does not count as a link on your page, so the credit line sits outside it in this version. Please keep it.

<iframe src="https://checkfitment.com/embed/frame/?w=wheel-spacer" title="Wheel spacer calculator" width="100%" height="700" style="border:0;max-width:640px" loading="lazy"></iframe>
<p><a href="https://checkfitment.com/wheel-spacer-calculator/">Calculator by CheckFitment</a></p>

Open the full wheel spacer calculator page →

Speedometer correction calculator

Real speed against shown speed after a tire size change, plus odometer error.

Snippet

<div data-checkfitment="speedometer"></div>
<script async src="https://checkfitment.com/embed.js"></script>

Iframe version, if your site does not allow scripts

An iframe works anywhere, but a link inside an iframe does not count as a link on your page, so the credit line sits outside it in this version. Please keep it.

<iframe src="https://checkfitment.com/embed/frame/?w=speedometer" title="Speedometer correction calculator" width="100%" height="520" style="border:0;max-width:640px" loading="lazy"></iframe>
<p><a href="https://checkfitment.com/speedometer-correction/">Calculator by CheckFitment</a></p>

Open the full speedometer correction calculator page →

Gear ratio after a tire change

The axle ratio your new tire size effectively behaves like, and the RPM change.

Snippet

<div data-checkfitment="gear-ratio"></div>
<script async src="https://checkfitment.com/embed.js"></script>

Iframe version, if your site does not allow scripts

An iframe works anywhere, but a link inside an iframe does not count as a link on your page, so the credit line sits outside it in this version. Please keep it.

<iframe src="https://checkfitment.com/embed/frame/?w=gear-ratio" title="Gear ratio after a tire change" width="100%" height="520" style="border:0;max-width:640px" loading="lazy"></iframe>
<p><a href="https://checkfitment.com/gear-ratio-after-tire-change/">Calculator by CheckFitment</a></p>

Open the full gear ratio after a tire change page →

Questions

Need a calculator that is not listed, or a version for another language? Write to info@checkfitment.com. For how the numbers are sourced, see how we verify.