The CharacterCounter for Joomla! does pretty much what it says. It counts characters in text fields in the Joomla! backend (Title, Alias, Meta Description, Browser Page Title, etc.). This way, you get immediate insight into the number of characters you have typed.
CharacterCounter is a small but very useful Joomla Extension for SEO purposes! Whenever you are typing in the Page Title field CharacterCounter will notice this and signals you if you have more than 55 characters. It also gives you a notice if the Meta Description is longer than 150 characters. This way you'll keep your text length within the generally accepted length based on SEO experts’ experience.
More precise the Google SERP (Search Engine Result Page) will display 512 pixels of the Page Title. Since a “W" is wider than an “I" the maximum number of characters may vary, but 55 is set as kind of a save zone.
And the best news… it’s free to use!