Dehumidifier Wattage for Generator Sizing
About the Dehumidifier
A portable or whole-house dehumidifier that removes moisture from the air using a compressor and heat exchanger. The starting surge comes from the compressor engaging. Dehumidifiers are especially important in basement and flood-prone areas where excess humidity can cause mold growth and structural damage. During extended power outages, running a dehumidifier can prevent costly moisture damage. Most units have a built-in humidistat that cycles the compressor on and off, so the actual duty cycle is less than continuous operation.
Generator Sizing for a Dehumidifier
Running a dehumidifier by itself requires a generator with at least 1,000 W of capacity (1 kW), which includes a 25% safety margin. However, you rarely run a single appliance on a generator. When combined with other appliances, the dehumidifier contributes 650 W to the continuous running load and adds a potential 150 W starting surge gap when its motor starts.
The dehumidifier is an inductive (motor-driven) load with a starting surge of 800 W, which is 1.2 times its running wattage. This starting surge occurs for a fraction of a second when the motor first engages and must overcome inertia to begin rotating. Your generator must be capable of delivering this peak wattage even though it only lasts briefly. If the dehumidifier has the largest starting surge gap of any appliance in your generator load, its surge gap of 150 W will be the primary driver of your peak demand calculation. Avoid starting the dehumidifier at the same time as other large motor loads to prevent generator overload.
To determine the total generator size you need, use our interactive calculator to combine the dehumidifier with your other appliances. The calculator automatically handles the starting surge calculation and applies the 25% safety margin to give you an accurate recommendation. Alternatively, browse the scenarios below to see common generator setups that include the dehumidifier.
Tips for Running a Dehumidifier on a Generator
When running the dehumidifier on a generator, the most important consideration is the starting surge. Before starting the dehumidifier, check that no other large motor-driven appliances are starting simultaneously. Stagger your startups: let the dehumidifier reach steady-state operation (usually within 1-2 seconds) before starting the next motor load.
If the generator struggles to start the dehumidifier (indicated by the generator bogging down, lights dimming significantly, or the appliance failing to start), it likely means the generator's peak surge capacity is insufficient. Try reducing other loads before attempting to start the dehumidifier again. If the problem persists, you may need a larger generator with more surge capacity.
Modern inverter generators handle motor starting surges particularly well due to their electronic power management. If you are purchasing a new generator specifically for loads that include the dehumidifier, verify that the generator's peak (starting) wattage specification meets or exceeds the 800 W starting requirement plus the running wattage of all other connected appliances.
Dehumidifier Wattage Compared to Similar Appliances
The following table compares the dehumidifier to other appliances in the hvac & climate category. Understanding relative power requirements helps you make informed decisions about which appliances to prioritize on your generator and where you might find opportunities to reduce your total load.
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Dehumidifier (this appliance) | 650 W | 800 W |
| Central Air Conditioner (3-Ton) | 3,500 W | 4,500 W |
| Window AC Unit (5,000 BTU) | 500 W | 600 W |
| Window AC Unit (10,000 BTU) | 1,200 W | 1,500 W |
| Portable Space Heater | 1,500 W | — |
| Furnace Blower Fan | 800 W | 1,300 W |
| Whole House Fan | 500 W | 800 W |
Frequently Asked Questions
How many watts does a dehumidifier use?
A dehumidifier uses approximately 650 watts of continuous (running) power during normal operation. It also requires 800 watts of starting (surge) power when the motor first turns on, which is 1.2 times the running wattage. This starting surge lasts only a fraction of a second but your generator must be capable of delivering it.
What size generator do I need to run a dehumidifier?
To run a dehumidifier by itself, you need a generator rated for at least 1,000 W (1 kW), which includes a 25% safety margin above the starting wattage of 800W. However, most people run additional appliances alongside the dehumidifier, so your actual generator needs will be higher. Use our calculator to add your other appliances and get a comprehensive recommendation.
Can I run a dehumidifier on an inverter generator?
Yes, a dehumidifier can run on an inverter generator as long as the generator's peak (starting) wattage capacity meets or exceeds 800 watts. Inverter generators handle motor starting surges well and provide clean power that is safe for the electronic controls found in many modern dehumidifier models. Verify the inverter generator's surge rating in the specifications.