Give your athletes the same pace, threshold, swim, power, heart-rate, and age-grade calculators used on Endurance Toolbox — right on your own website. Copy one snippet, paste it into any page, done.
Free, no signupUse them on club, coaching, race, and school sites.
No ads or trackingEmbeds load no analytics or ads; calculations run in the browser.
Fits your pageResponsive down to phone widths and auto-resizes to its content.
How to embed
Pick a calculator below and copy its snippet.
Paste it into an HTML / "custom code" block on your site (WordPress, Squarespace, Wix, Webflow, and Google Sites all support this).
Keep the one-line credit under the calculator — it's the only thing we ask in return.
The optional /embed.jsscript resizes the frame to fit the calculator. Without it the frame keeps its fixed height. For miles instead of kilometres, add?units=imperialto the frame URL of pace-based calculators.
Live preview: VDOT Calculator & Race Predictor
This is exactly what visitors to your site will see.
<iframe src="https://www.endurancetoolbox.com/embed/threshold-run" title="30-Minute Run Threshold Calculator by Endurance Toolbox" data-endurance-toolbox="threshold-run" width="100%" height="1500" style="width:100%;max-width:960px;border:0;" loading="lazy"></iframe>
<p><a href="https://www.endurancetoolbox.com/widgets/threshold-run">30-Minute Run Threshold Calculator</a> by Endurance Toolbox</p>
<script src="https://www.endurancetoolbox.com/embed.js" async></script>
VDOT Calculator & Race Predictor
Enter a recent race to get your VDOT score, equivalent times from 1500m to marathon, and easy, threshold, and interval paces from the Daniels equations.
<iframe src="https://www.endurancetoolbox.com/embed/power-zones" title="Cycling Power Zones (FTP) by Endurance Toolbox" data-endurance-toolbox="power-zones" width="100%" height="800" style="width:100%;max-width:960px;border:0;" loading="lazy"></iframe>
<p><a href="https://www.endurancetoolbox.com/widgets/power-zones">Cycling Power Zones (FTP)</a> by Endurance Toolbox</p>
<script src="https://www.endurancetoolbox.com/embed.js" async></script>
PacePro - Race Pace Calculator
Calculate running pace per km and mile, cumulative race splits, and equivalent times for 5K, 10K, half marathon, or marathon goals.