beantin

Monitoring and analysing the size of the browser windows of your visitors is crucial for you to optimise the experience, design and conversion rate of your site. More than ever with the advent of responsive web design. This plugin gathers viewport data and stores it in Google Analytics.
Using a javascript event triggered by the onload event, this plug in measures the browser viewport size of your visitor’s browser and sends the result to your Google Analytics account as an event.
You must have the asynchronous Google Analytics tracking script installed on your site and use _gaq as the object name. 
The template you are using must support the body_class filter hook introduced in wordpress 2.8
Details on the technique behind this solution can be found here http://beantin.se/post/354097397/track-viewport-google-analytics
To view the results, log in to your Google Analytics account (but wait a day for GA to process the data) and look at Content -> Events -> Top Events.
In that report you will see and event called “Viewport” with three actions; “Width”, “Height”, and “Size”. The label within the action “Size” shows the exact dimensions of the browser viewport size of each visitor to your site.

Measure Viewport Size

Captures the viewport size of visitors' browser window and stores it as events in Google Analytics

wppluginexpert

w2pe Measurement Widget is a simple measurement converter. You can use both in page or widget. There is a possibility to add custom units in admin area and edit or delete units. 
Measurements and units included as presets: 
* Area – foot, inch, meter, mile, kilometer 
* Currency – Bangladeshi TK, British pound, Euro, Indian rupee, Japanese Yen, US dollar 
* Length – kilometer, meter, mile, yard 
* Mass – gram, kilogram, pound, ton 
* Temperature – Celsius, Fahrenheit, Kelvin
<h4>How to use?</h4>
<ol>
<li>If you want to use in widget, use “w2pe Measurement Widget”</li>
<li>If you want to use in a page or post, use [w2pe_measurement]</li>
</ol>

w2pe Measurement Widget

w2pe Measurement Widget is especially designed to make your units conversion job a whole lot easier. Here you'll find instant conversions for tho …

Measure Viewport Size vs w2pe Measurement Widget