Best overall
Honda EU2200i
2,200W start · 1,800W run
Gasoline · Inverter · 48–57 dBA · 47 lb
The benchmark quiet inverter — legendary engine reliability and clean power (<3% THD) for sensitive electronics.
Find on AmazonWhat size generator to run a garage door opener (1/2 hp)?
Short answer
A garage door opener (1/2 hp) draws about 550 running watts but surges to roughly 1,100 starting watts when its motor kicks on, so you need a generator rated for at least 1,100 starting watts to run one on its own — a 2,000W unit gives comfortable headroom.
Running watts
550W
Starting watts
1,100W
Minimum generator
1,100W
Recommended
2,000W
Sizing a generator for a garage door opener (1/2 hp)
A garage door opener (1/2 hp) runs at about 550 watts, but its motor briefly pulls 1,100 starting watts — 550 extra — for a fraction of a second when it kicks on. That surge, not the running figure, sets the minimum generator size, which is why a generator sized only on running watts can stall the moment the motor starts.
To run one on its own, choose a generator rated for at least 1,100 starting watts. To run it alongside other essentials, add up everything you need and size up — the calculator below does that math for your exact list.
Run your full appliance list
This page covers the garage door opener (1/2 hp) on its own. Open the calculator with it pre-selected, then add everything else you plan to power at the same time.
Size a generator with a garage door opener (1/2 hp)Recommended recreational / portable generators
Real, widely available units in the Up to 3,500W class. Independent picks — we're not affiliated with any manufacturer or retailer and earn nothing from these links.
Best value
Westinghouse iGen2200
2,200W start · 1,800W run
Gasoline · Inverter · 52 dBA · excellent fuel economy
Matches the Honda’s 1,800W running output for a fraction of the price, and sips even less fuel.
Find on AmazonBudget pick
Champion 2500W Dual Fuel Inverter (201183)
2,500W start · 1,850W run
Dual fuel (gas / propane) · Inverter · CO Shield auto-shutoff · ultralight
Runs on gasoline or propane and includes a built-in carbon monoxide shutoff sensor.
Find on AmazonFrequently asked questions
What size generator do I need to run a garage door opener (1/2 hp)?
To run a garage door opener (1/2 hp) on its own you need a generator rated for at least 1,100 starting watts. We recommend a 2,000W (recreational / portable) unit so you have headroom to add other appliances without running the generator at its limit.
How many watts does a garage door opener (1/2 hp) use?
A garage door opener (1/2 hp) uses about 550 running watts continuously, and briefly spikes to roughly 1,100 starting watts (550 extra) at the instant its motor kicks on. Always check your unit's nameplate for exact figures.
Why does a garage door opener (1/2 hp) need more starting watts than running watts?
Its motor needs a short burst of extra power — usually 2-3x its running wattage for a fraction of a second — to overcome inertia and get moving. That surge is what actually determines the generator size, which is why sizing on running watts alone leaves you short.