Starting today, any tweet sent with a URL will be reduced to 118 characters, or 117 for https links.
While this may seem like a huge drop, the change represents a two-character drop per tweet from what you are currently able to send when a hyperlink is involved.
Why is this happening? In December Twitter announced that they would be extending the t.co wrapper length–there by decreasing tweet length.
Still not sure what this means? Well in simple terms you may want to consider using a URL shortner, like Google or Bitly, when posting links in your tweets. If you don’t use a URL shortner in your tweets just know you’ll be down 1 character.