What Can a Portable Generator Power?
A portable generator can power a wide range of appliances, tools, and essential devices — but only within its wattage limits.
Many users assume that if a generator is running, it can power anything plugged into it. In reality, what a portable generator can power depends on several factors, including running watts, starting watts, load combinations, and real-world operating conditions.
This guide explains what portable generators can realistically power in common scenarios, how to calculate safe loads, and what limitations you should expect.
The Key Factor: Generator Wattage
Every portable generator is defined by its wattage capacity. This capacity determines what devices it can run and how many can operate at the same time.
Generators are rated using two numbers:
- Running watts: the continuous power the generator can supply
- Starting watts: the temporary peak power required to start motors or compressors
Many appliances with motors — such as refrigerators, pumps, and air conditioners — require significantly more power for a few seconds when starting than they do while running.
Ignoring starting watts is one of the most common causes of generator overload.
Typical Appliance Wattage (Real-World Estimates)
The table below shows approximate wattage requirements for common household and portable devices. Actual values vary by model, but these ranges are useful for planning.
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Refrigerator | 600–800 | 1,800–2,200 |
| Freezer | 500–700 | 1,500–2,000 |
| Microwave | 1,000–1,500 | Same as running |
| Sump Pump (1/2 HP) | 1,000 | 2,000–3,000 |
| Window AC Unit | 1,000–1,400 | 2,000–3,000 |
| Space Heater | 1,500 | Same as running |
| Television | 100–300 | Same as running |
| Laptop | 50–100 | Same as running |
| Coffee Maker | 800–1,200 | Same as running |
| LED Lighting (multiple) | 100–200 | Same as running |
These numbers help illustrate why even a mid-size generator can become overloaded if multiple appliances start at the same time.
What Small Portable Generators (1,000–2,000 Watts) Can Power
Small portable generators are lightweight, fuel-efficient, and commonly used for camping or basic emergency needs.
They can typically power:
- LED lights
- Phones, tablets, and laptops
- Wi-Fi routers or modems
- Small fans
- CPAP machines (check specifications)
They usually cannot power:
- Refrigerators or freezers
- Microwaves
- Space heaters
- Motor-driven power tools
These generators are best suited for low-power electronics and short-term use, not full home backup.
What Mid-Size Portable Generators (3,000–4,000 Watts) Can Power
Mid-size generators are the most common choice for home backup during outages.
They can often power:
- Refrigerator or freezer
- Microwave
- Sump pump
- Television and lighting
- Small window air conditioner
- Power tools (one at a time)
Load management is critical at this level. Starting multiple motor-driven appliances simultaneously can exceed the generator’s starting watt capacity, even if total running watts appear acceptable.
What Large Portable Generators (5,000–7,500 Watts) Can Power
Large portable generators provide significantly more flexibility and can support multiple systems at once.
They can typically power:
- Refrigerator and freezer together
- Furnace blower or boiler controls
- Well pump
- Multiple rooms of lighting
- Larger power tools
However, even large portable generators are not designed to power an entire house continuously without careful planning or a transfer switch.
Common Load Combination Examples
Understanding individual appliance wattage is helpful, but real-world use depends on combinations.
Can a portable generator run a refrigerator and microwave at the same time?
It depends on the generator’s starting watt capacity.
- Refrigerator starting watts: up to 2,200
- Microwave running watts: up to 1,500
If both appliances start simultaneously, the combined surge may exceed the generator’s limits. Starting the refrigerator first and waiting before using the microwave often prevents overload.
Can a generator run a sump pump and lights during an outage?
Yes, in many cases.
- Sump pump starting watts: up to 3,000
- LED lighting: 100–200 watts
A mid-size generator can usually handle this load if no other high-watt appliances are running.
Can I run power tools continuously?
Most portable generators can run power tools, but usually one at a time.
Tools with motors, such as air compressors or table saws, draw high starting current and should not be used simultaneously on smaller generators.
What Portable Generators Usually Cannot Power
Regardless of size, most portable generators are not suitable for powering:
- Central air conditioning systems
- Electric water heaters
- Electric ovens or ranges
- Whole-house HVAC systems
- Large electric dryers
These appliances require sustained high wattage that exceeds the safe operating range of portable units.
Factors That Affect Real-World Generator Output
A generator’s rated wattage is measured under ideal conditions. Real-world output can be reduced by several factors.
Altitude
At higher elevations, engines produce less power due to reduced air density. Output can drop by several percent for every 1,000 feet of elevation.
Temperature
High ambient temperatures reduce engine efficiency and cooling performance, lowering available power.
Fuel Type
Propane-powered generators often produce slightly less wattage than gasoline when using the same engine.
Generator Age and Maintenance
Worn engines, dirty air filters, or improper maintenance can reduce output and reliability over time.
Common Mistakes When Estimating Generator Capacity
Many generator problems come from incorrect assumptions rather than equipment failure.
Common mistakes include:
- Adding only running watts and ignoring starting watts
- Attempting to power too many devices at once
- Using undersized or damaged extension cords
- Assuming peak wattage equals continuous capacity
Avoiding these mistakes significantly improves safety and reliability.
Managing Loads Safely
Safe generator use depends on managing electrical loads carefully.
Best practices include:
- Starting high-wattage appliances one at a time
- Turning off unnecessary devices
- Monitoring total running wattage
- Leaving headroom for startup surges
- Using outdoor-rated extension cords
Overloading a generator can cause voltage drops, tripped breakers, or automatic shutdown.
Frequently Asked Questions
Can a portable generator run a refrigerator all day?
Yes, if the generator has sufficient capacity and fuel. Many users cycle refrigerators on and off to conserve fuel during long outages.
Can a portable generator power a house overnight?
A portable generator can power essential circuits overnight, but not an entire house. Load planning and fuel management are critical.
Can portable generators power sensitive electronics?
Yes, but voltage stability matters. Inverter generators are generally better suited for sensitive electronics than conventional models.
Why Understanding Capacity Matters
Knowing what a portable generator can realistically power helps users avoid overloads, protect equipment, and operate generators more safely.
Rather than focusing on maximum wattage claims, planning around real-world usage and safe load combinations leads to better outcomes during outages, outdoor use, or job site work.
Related Guides
- What Is a Portable Generator?
- How Does a Portable Generator Work?
- How Many Watts Do I Need for a Portable Generator?
- Portable Generator Safety Checklist
Choosing the Right Generator Type
Once you understand your power needs, these comparisons help you choose the right generator design: