From the always useful How-To Geek web site, this report disproves the common view that all of those portable gadget chargers (cell phone, digital camera, etc.) you have plugged in around your house (I counted and we have more than 20 ""wall warts" or similar chargers hanging from various outlets around the house) use a lot of electricity.
According to the article, the How-To Geek writer used a Kill a Watt meter to test chargers for the iPhone, iPad, MacBook, Chromebook, Windows laptops, Android phones. Individually, each charger rang up a big 0.0 watts of power usage. Then the writer filled an entire power strip with six different chargers. He got a total reading of 0.3 watts. Even if you have the most expensive electricity in the country (Hawaii), the cost for all six COMBINED is less than a dollar per year when they are plugged in but not charging their respective devices.
Go ahead and keep your chargers plugged in if unplugging them is too much of a pain. The cost is almost non-existent.