What Size Generator for a Garage Door Opener?
A 2,200W inverter covers a garage door opener several times over: a 1/2 HP opener draws about 550 watts running and 1,100 starting, for the ten seconds it takes the door to move. Before sizing a generator for this at all, pull the red release cord; every opener has one, and it makes the door hand-operable for free.
Wattage by type
| Garage door opener type | Running | Starting |
|---|---|---|
| 1/3 HP chain drive | 400 W | 800 W |
| 1/2 HP (planning number) | 550 W | 1,100 W |
| 3/4 HP belt drive | 650 W | 1,300 W |
| 1.25 HP with battery backup | 700 (self-charging) W | 1,400 W |
What it takes with company
Same engine as the wattage picker: running total plus the single biggest start spike, then the smallest class that carries it with 20% headroom.
| Load list | Running | Peak | Buy |
|---|---|---|---|
| Opener alone | 550 W | 1,100 W | 2,200W inverter |
| Opener + fridge + the basics (garage circuit) | 1,450 W | 2,950 W | 3,400W inverter |
The details that change the answer
This page exists because the question gets asked every hurricane season, and the honest answer is a hierarchy. First: the red emergency release cord disconnects the trolley and the door lifts by hand, no watts required (lock it afterward; a released door isn't latched). Second: openers sold in the last decade often have battery backup built in, good for a few dozen cycles, because California mandated it in 2019 and manufacturers standardized. Only third comes generator power, and by then the opener is a rounding error on whatever unit is already running the fridge.
The load itself is a small induction motor with the usual doubling at start, plus 5 to 10 standby watts for the radio and the LEDs. Ten seconds of 550W per cycle rounds to nothing in fuel terms. If the opener is the only thing you'd want power for, don't buy a generator; buy the battery-backup opener head unit when the current one dies, and pull the red cord until then.
Questions people ask
How do I open the garage door when the power is out?
Pull the red release cord hanging from the opener rail; it disconnects the door from the motor and the door lifts by hand. This works from inside with no power and no generator. From outside on a closed door you need the exterior key release if one is fitted, which is worth checking exists before the storm rather than during it.
Is it worth running a generator for the garage door?
On its own, no; the release cord is free and battery-backup openers cost less than any generator. As one more load on a generator already running the house, sure: 550 watts for ten seconds barely registers on a 3,500W unit. Just don’t let the opener be the reason you buy anything.