How much does standby power actually cost?
Standby draw is real but small, and the advice built around it is mostly misdirected. What is worth unplugging, and what is not.
Reviewed
The numbers are smaller than the advice suggests
Standby power — the draw of a device that is switched off but still plugged in — was a genuine problem two decades ago, when set-top boxes and televisions could idle at 20 watts or more.
Regulation and better power supplies have largely fixed it. A modern television draws well under one watt in standby. A phone charger with nothing attached draws a small fraction of a watt.
Unplugging a phone charger saves a few cents a year. It is not a meaningful lever on a bill, and treating it as one distracts from the changes that are.
What is still worth unplugging
Anything that is not truly idle. A games console left in a fast-resume mode, a desktop computer asleep rather than shut down, or a set-top box that records continuously can draw ten to twenty watts around the clock.
Old appliances predating modern standby rules, particularly a second television or stereo in a spare room.
A second refrigerator or freezer running nearly empty. This is not standby at all — it is a full appliance — and it is the one 'plugged in and forgotten’ item that genuinely costs real money.
A better use of the same attention
Standby is a rounding error next to heating, cooling and water heating. If the goal is a lower bill, the order of attack should follow the size of the load.
The exception is worth repeating, because it is common: an idle second fridge in a garage can cost more per year than every standby load in the house combined.