What Size Generator Do You Need to Run a Garage Door Opener?
By the Generator Size Calculator Team · Updated · 5 min read
Quick answer: Honda lists a garage door opener at 550 running and 1,100 starting watts for 1/4 HP and 725 and 1,400 for 1/3 HP. A 2,000-watt inverter generator runs one on its own, and a 3,000-watt generator runs an opener with a refrigerator and lights. The opener only draws power while the door moves, so it is a very short load.
Opener watts
| Garage door opener | Running watts | Starting watts |
|---|---|---|
| 1/4 HP | 550 | 1,100 |
| 1/3 HP | 725 | 1,400 |
A garage door opener's motor runs only while the door travels, usually for 10 to 20 seconds, so it adds very little to a generator's load over time. The standby draw of the opener's light and receiver is small. Check the label for the horsepower.
Which generator size to choose
| Setup | Running load | Generator |
|---|---|---|
| 1/4 HP opener alone | 550 W | 2,000 W inverter |
| 1/3 HP opener alone | 725 W | 2,000 W inverter |
| 1/3 HP opener, fridge, TV, lights, Wi-Fi | 1,900 W | 3,000 W |
For the last row, the fridge's start-up surge of about 1,500 watts sits on top, so the peak is about 3,400 watts. A 3,000-watt generator has a running limit at 80% of 2,400 watts and about 3,750 starting watts, so it fits. If everything is already running, the opener adds only a short bump. For the fridge, see generator size for a refrigerator.
List the opener and everything else in one go.
Tips
- Use the manual release if you only need to open the door once, and save the generator for the fridge. Check your opener's manual.
- Open the door before starting other loads so the opener's surge doesn't stack with a compressor.
- Never run the generator in the garage, even with the door open.
- Plug the opener into a GFCI outlet or follow your electrician's advice for the circuit.
Run the generator outdoors, at least 20 feet from doors, windows and vents. Never in a garage or shed, even with the door open. The garage is the most dangerous place to run one, even with the big door up. See how far a generator should be from your house.
Frequently asked questions
How many watts does a garage door opener use?
Honda lists a 1/4 HP opener at about 550 running and 1,100 starting watts, and a 1/3 HP at 725 and 1,400.
Can a 2000-watt generator run a garage door opener?
Yes, on its own, since 1,400 starting watts is within a typical 2,000-watt peak.
Can a generator run a garage door opener and a fridge?
Yes. A 3,000-watt generator covers an opener, a fridge, a TV, lights and Wi-Fi.
Can I just open the door by hand?
Most openers have a manual release. Check your manual and keep the door balanced and safe.
Can I run the generator inside the garage?
No. Carbon monoxide builds up even with the door open. Keep it outdoors, 20 feet from the house.
Related calculators
Sources: Running and starting watts from the Honda generator wattage guide (garage door openers, refrigerator). Generator sizes apply the 80% running rule and an assumed starting capacity about 25% above rating.