A heating element is stitched through the robe's lining and draws power from the wall through an inline controller on the cord. The controller sets which heat level the element runs at and how long before it shuts itself off. From cold, a heated robe reaches temperature in about a minute.
People assume “heated robe” means thick fleece and marketing. It doesn't. There is real wiring in it, and understanding the three parts tells you most of what you need to know before buying one.
The element
A heating element runs through the sherpa lining, spread across the robe rather than concentrated in one panel. Spread matters: it is the difference between a robe that is warm everywhere and one with a hot patch between the shoulder blades.
The controller
An inline controller sits on the cord between the robe and the outlet. It does two jobs — choosing the heat level and setting the shut-off timer. On ours there are five levels and a timer offering 1, 2, 4, 6 or 8 hours.
The controller also detaches, which is the part people overlook when comparing robes. A detachable controller is what lets the robe go in a washing machine.
Why about a minute matters
Time to temperature decides whether you actually use the thing. If warming up takes a quarter of an hour, you will put a jumper on instead. About a minute means you reach for it because you are cold right now.
What the sherpa is doing
Holding the heat in. The element produces warmth and the lining stops it escaping — which is why the lining being sherpa throughout, rather than one panel, changes how the whole robe performs. It also means the robe stays warm unplugged, which is how you wear it once the timer has run out.
And the foot pocket
Heat rises. In a floor-length robe that means warmth travels up and out at the hem, taking the heat away from the coldest part of you. Folding the hem back into a lined foot pocket closes that gap and keeps the warmth around your feet.
Before you buy one, here is what to look for.