Meta Box Text Limiter Plugin
Text Limiter is an extension for Meta Box plugin which allows you to limit number of characters or words entered for text and textarea fields.
Usage
To start using text limiter, just add the following parameters to text or textarea fields:
'limit' => 20, // Number of characters or words
'limit_type' => 'character', // Limit by 'character' or 'word'. Optional. Default is 'character'