Running watts and surge watts for every common household appliance, organized by category. Use this reference to calculate your generator size requirements accurately.
Generator sizing rule: Your generator's peak (surge) rating must exceed the highest surge watt value in your list. A 5,000W generator with a 6,500W surge handles all four appliances above — even the 3,600W window AC spike.
How to Use This Wattage Chart for Generator Sizing
This chart gives you the running and surge wattage for every common household appliance. Here's how to use it to size your generator:
Find each appliance you want to power in the chart above.
Note the running watts for each appliance.
For motor-driven appliances (AC units, pumps, compressors), note the surge watts.
Add all running watts together — this is your total continuous load.
Find the single appliance with the highest surge watts.
Divide total running watts by 0.8 to get your minimum generator running wattage.
Verify your chosen generator's starting watts exceed the highest surge load.
Most people focus on running watts when sizing a generator, but surge (starting) watts are often the real limiting factor. A common scenario: you buy a 3,500-watt generator, hook up your refrigerator and sump pump, and the generator immediately shuts down on overload.
What happened? Your refrigerator and sump pump together might only draw 950 watts continuously — well within the 3,500-watt rating. But if the sump pump motor tried to start while the refrigerator compressor was also starting, the combined surge could hit 4,500–5,000 watts, tripping the generator's overload protection.
The solution is twofold: (1) Size your generator with surge headroom — don't plan to run at 100% continuous load. (2) Stagger the startup of large motors — don't start the refrigerator and AC unit simultaneously. Modern smart generators can handle some load sequencing, but manual awareness is important.
Surge Multiplier Explained
The surge multiplier column in the chart above shows how many times the running watts a motor needs to start. Here's what the colors mean:
3.5–4× (Red): Very high surge load. Central AC units, air compressors, and heavy pumps. Requires significant generator headroom above running load.
2.5–3.5× (Orange): High surge. Refrigerators, window AC units, sump pumps. Must be accounted for in generator sizing.
1.1–2.5× (Yellow): Moderate surge. Some power tools, smaller motors. Typically manageable with normal safety margins.
1× (Gray): No meaningful surge. Resistive loads like heaters, lights, and most electronics. Size purely on running watts.
How to Read the Wattage Chart
Motor Starting Surge Explained
The surge watts column in the wattage chart above reflects Locked Rotor Amps (LRA) — the current required to start an induction motor from rest. Electric motors in refrigerators, AC compressors, pumps, and power tools all use induction, and consequently all require a startup surge of 2–4× their running watts. However, this surge lasts only 0.5–2 seconds before the motor reaches operating speed. Therefore, your generator does not need to sustain the surge — it only needs to produce it briefly without tripping its overload protection.
Running Watts vs. Rated Watts
Appliance wattage ratings on the nameplate (in watts or amps) typically represent the maximum draw under full load, not the actual average running draw. For example, a refrigerator rated at 200W nameplate actually runs at 100–150W continuously, with brief compressor cycling that draws 150–200W. Consequently, real-world running watts are often lower than nameplate ratings. Furthermore, when performing a full load calculation, use the running watts figures from the chart above (based on typical usage), not the nameplate maximum.
120V vs. 240V Appliances
Most household appliances operate on 120V, however some high-draw appliances (electric dryers, large water heaters, central AC, electric ranges) require 240V. Watts (power) is the same regardless of voltage — however, at 240V, the current (amps) is half what it would be at 120V. Therefore, your generator must output 240V for large appliances, not just 120V. Additionally, most portable generators above 3,500W provide 240V output, but verify this on the spec sheet — some cheaper models output only 120V even at higher wattages.
Use the Wattage Chart in Our Calculator
Select appliances from the chart above in our interactive calculator to instantly get your generator size recommendation.
