What Size Generator Do You Need to Run a Dehumidifier?
By the Generator Size Calculator Team · Updated · 5 min read
Quick answer: Honda lists a dehumidifier at 650 running watts and 800 starting watts. A 2,000-watt inverter generator runs one on its own, and a 3,500-watt generator runs a dehumidifier with a 1/2 HP sump pump and lights. A dehumidifier is a steady load that can run for many hours, so plan for fuel as well as watts.
Dehumidifier watts
| Appliance | Running watts | Starting watts |
|---|---|---|
| Dehumidifier | 650 | 800 |
| Sump pump, 1/3 HP | 750 | 1,500 |
| Sump pump, 1/2 HP | 1,000 | 2,100 |
These are Honda's typical figures. A small unit may draw less and a large basement unit more, so check the label. The compressor needs only a modest surge, about 150 watts above running, much less than a sump pump.
Which generator size to choose
| Setup | Running load | Generator |
|---|---|---|
| Dehumidifier alone | 650 W | 2,000 W inverter |
| Dehumidifier and a 1/3 HP sump pump | 1,400 W | 3,000 W |
| Dehumidifier, 1/2 HP sump pump and lights | 1,825 W | 3,500 W |
For the pump alone, see what size generator a sump pump needs.
Example: dehumidifier, sump pump and lights
| Load | Running watts |
|---|---|
| Dehumidifier | 650 |
| Sump pump, 1/2 HP | 1,000 |
| Lights, chargers, Wi-Fi | 175 |
| Running total | 1,825 |
The sump pump's extra start-up load is about 1,100 watts, larger than the dehumidifier's, so the peak is about 2,925 watts. A 3,500-watt generator carries 1,825 running watts under its 80% mark (2,800 watts), and its approximate 4,400-watt starting capacity covers the peak.
Fridge, furnace fan and more on the same list.
Tips
- Run it in a closed room with the door shut, and empty the bucket or use a drain hose.
- Run the cord out, not the generator in. A basement is never a safe place for a generator.
- Plan the fuel. A dehumidifier may run for many hours, so see how long a generator runs on a tank of gas.
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 basement or garage is not a safe spot, even when the dehumidifier is down there. See how far a generator should be from your house.
Frequently asked questions
How many watts does a dehumidifier use?
Honda lists a dehumidifier at about 650 running and 800 starting watts. Large basement units may use more.
Can a 2000-watt generator run a dehumidifier?
Yes, a typical unit on its own, with room for lights and a router.
Can I run a dehumidifier and a sump pump on one generator?
Yes. A dehumidifier, a 1/2 HP sump pump and lights total about 1,825 running watts and a peak near 2,925 watts, which fits a 3,500-watt generator.
Can I run the generator in the basement?
No. Keep it outdoors, at least 20 feet from doors, windows and vents, and run a cord inside.
Does a dehumidifier have a starting surge?
A small one, about 800 starting watts versus 650 running.
Related calculators
Sources: Running and starting watts from the Honda generator wattage guide (dehumidifier, sump pumps). Generator sizes apply the 80% running rule and an assumed starting capacity about 25% above rating.