title_body: How much of the power does the screen of e-Ink device consume?
upvoted_answer: I beleive you are asking "can the power usage of an eink screen be quantified?"
  
  As long as you don't change the page/image it is not using anypower. 
  
  
    E Ink's technology is commonly referred to as "bistable". What does this mean? Bistable means that the image on an E Ink screen will be retained even when all power sources are removed. In practice, this means that the display is consuming power only when something is changing. For example, when reading on an eReader, power is only needed when turning to a new page but no power is consumed by the display while reading the page. - See more at: http://www.eink.com/technology.html
  
  
  To quantify a value for usage while reading you would need to define; 
  
  
  The make and model of your device
  If you are using device lighting and if so at what level
  The rate of page turning