If you’ve ever watched the lights blink out just as dinner’s ready, or piled everyone into the car to charge phones, you know a power outage can throw a whole evening off course. A standby generator can make those moments a lot less stressful. But the right generator size matters: too small, and it may struggle with the loads you need; too large, and you may spend more than your home requires.
So, what size standby generator does your Dallas home actually need? The honest answer is: it depends on what you want to keep running, how those appliances start up, and what your home’s electrical system can support. Here’s a simple guide to what goes into the decision.
Why generator size matters
A standby generator’s capacity is measured in kilowatts (kW). It needs to supply enough power for the appliances and systems you want to operate at the same time, including the extra power some equipment needs when it starts.
An undersized unit may have trouble starting large appliances or supporting several loads at once. That can mean managing what’s on, or having a system that can’t deliver the backup power you expected. An oversized unit can mean paying for capacity you won’t use.
The goal isn’t to buy the biggest generator. It’s to size the system for your home and the way your family lives.
First decide: whole house or essential loads?
“Whole house generator” is a familiar term, but it doesn’t always mean every appliance can run at the same time. Some homeowners want backup for nearly everything in the home. Others prioritize essential circuits (such as refrigeration, lighting, internet, and selected heating or cooling) and are happy to manage the rest during an outage.
Think about a typical summer evening. Would you expect the central air conditioner to run while the oven, dryer, and pool equipment are also in use? Or would you be comfortable postponing some of those loads until the power returns? Your answer can change the size and configuration of the system.
What goes into a proper sizing evaluation?
A professional sizing evaluation looks beyond your home’s square footage. The important question is how much power the selected loads need, both while running and when starting.
A load calculation typically considers:
- Your electrical panel and service: What circuits are available, and what do you want the generator to support?
- Major appliances: Think about electric ranges, dryers, water heaters, and other high-demand equipment.
- Heating and cooling: Your air conditioner or heat pump can be one of the biggest factors.
- Motors and pumps: Pool equipment, well pumps, and similar equipment can need an extra burst of power to start.
- What may run together: Sizing should reflect realistic combinations of loads, not just a list of everything in the house.
- Fuel and generator specifications: The actual output depends on the specific generator and fuel configuration.
This is why adding together the breaker numbers, or choosing a generator based on square footage alone, doesn’t give you a reliable answer. The details on equipment nameplates and the loads your system can connect are important.
A useful starting range, not a final answer
For many U.S. homes, whole-house standby generator sizes fall roughly in the 14–26 kW range. That’s a broad planning range, not a recommendation for every Dallas home.
A smaller, carefully managed load may fit toward the lower end. A home with multiple air-conditioning systems, electric appliances, or several large loads that may operate together could need more capacity, or a load-management setup that controls what runs at once. A larger generator isn’t automatically the right answer, either. The calculation has to match your home.
The model’s fuel-specific output matters, too. Don’t assume that the number in a model’s name tells the whole story: ask your installer to confirm the output for the fuel and installation being considered.
Dallas note: don’t overlook air-conditioner startup
In North Texas, air-conditioning is a key sizing consideration. A cooling system draws power as it runs, but its compressor may also need additional power at startup. That brief demand can affect the generator size needed to start the system reliably, especially if the home has more than one A/C unit.
A technician can review the equipment specifications and determine how the air conditioner fits into your home’s load calculation. In some cases, load management or an appropriate soft-start solution may be worth discussing. Those options should be evaluated for the specific equipment; they aren’t a substitute for checking the system’s requirements.
Natural gas or propane?
Fuel choice is part of sizing and planning. Natural gas and propane systems have different site requirements, and your property’s fuel supply needs to support the generator. If you’re comparing the two, read our guide to propane vs. natural gas for home generators.
The important thing is to look at fuel availability and installation requirements alongside the generator’s power needs, not to pick a unit first and assume the rest will work itself out.
Why an online calculator isn’t the final word
Online tools can help you make a list of appliances and start thinking through priorities. But they can’t always verify your equipment’s starting requirements, inspect your panel, or assess how the generator and transfer equipment will work at your property.
A professional evaluation connects the numbers to the actual home. It can help you compare a whole-house setup with essential-load backup, identify whether load management makes sense, and flag installation requirements before you commit to a particular system.
What about commercial generators?
Business sizing follows the same basic idea, match the generator to the loads and operating priorities, but the needs can be very different. A business may need backup for refrigeration, production equipment, communications, safety systems, or multiple building systems. Commercial generator sizes vary widely, so there’s no useful one-size-fits-all number. The right starting point is a review of the facility’s power needs and what operations must continue during an outage.
Prepare thoughtfully, not fearfully
DFW winter outages are often local problems, such as ice-damaged lines or tree limbs, rather than an ERCOT grid failure. The 2026–27 winter outlook is milder, with ERCOT energy-emergency risk around 3% during the riskiest hours and El Niño favoring warmer-than-normal conditions. That’s not a reason to assume a major grid emergency is around the corner. It’s also no guarantee that your neighborhood won’t experience a localized outage.
The practical question is what you’d want powered if your home lost electricity for a while. A clear plan, and a generator sized to match it, can help you make that decision without guessing.
Get a free sizing evaluation
At Verdegy, we install and maintain Kohler standby generators for Dallas-area homes. Our Kohler-trained technicians can review your electrical loads, help you decide what you want backed up, and provide a free consultation and sizing evaluation. We’ve served DFW since 2007, are A-rated with the BBB, and handle turnkey generator installation, including permits and inspections.
If you’re starting to compare options, contact us to talk through your home and what you want to keep running. We’ll help you find a practical fit, no guesswork required.
Call us for a quote (leave a message): 214-207-0506.