flaracca

Convert time/distance (either mins/km or mins/mile) to distance per hour (kph or mph).

LRF speed converter

Convert time/distance (either mins/km or mins/mile) to distance per hour (kph or mph).

danbwb

Simple to use Unit Converter Plugin for WordPress. It displays both in Metric and Imperial units. For the time, you can use the following categories:
<pre><code>Length / Distance Converter
Temperature Converter
Time Converter
Weight Converter
Area Converter
Speed Converter
</code></pre>
The plugin creates a shortcode so you can display these converters either in posts / pages or inside a sidebar within a text widget.
New features in version 1.1.1
<ul>
<li>Fixed working with jQuery 1.9+</li>
</ul>

Oppso Unit Converter

Simple to use Unit Converter Plugin. It displays both in Metric and Imperial units.

LRF speed converter vs Oppso Unit Converter