When the power goes out, the generator you need depends on what you want to keep running. Keeping the refrigerator, a few lights, and your internet online requires far less capacity than powering central air conditioning, an electric water heater, and several large appliances at the same time.
That is why generator sizing should start with your household’s actual electrical loads, not square footage alone. This guide explains running watts, starting demand, major appliances, and the other factors that help determine what size generator makes sense for your Texas home.
Why Generator Size Matters
Generators are rated by how much electrical load they can support, typically measured in watts or kilowatts (kW). Every appliance or device adds to that load, and some equipment needs extra power to start. Your generator needs enough capacity to handle both normal operation and startup demand without exceeding what the unit can support.
The type of generator matters too. A portable generator typically powers selected essential loads, while a permanently installed standby generator can connect to the home’s electrical system through appropriate transfer equipment and be sized for a broader group of circuits. Don’t choose either option based on home size alone.
How to Figure Out What Size Generator You Need
No single generator size works for every Texas home. Two houses with the same square footage can have completely different electrical demands depending on their HVAC equipment, appliances, pumps, and what the homeowners want available during an outage.
1. Decide What You Need to Power
Start by deciding what you actually want to keep running. Some homeowners want backup power for essentials, while others want enough capacity to maintain cooling, kitchen appliances, and most of the home during an extended outage.
Common priority loads may include:
- Refrigerator and freezer
- Lights in frequently used rooms
- Internet equipment, chargers, and selected outlets
- Sump pump or well pump, if applicable
- Medical equipment that requires continuous power
Consider heating and cooling equipment separately because it can represent a significant portion of the home’s electrical demand. Creating a must-have list first keeps the sizing calculation focused on the equipment you would genuinely use during an outage.
2. Add Up the Running Watts
Running watts are the amount of power an appliance uses while operating normally. You can usually find the electrical requirements on the equipment label, in the owner’s manual, or in the manufacturer specifications.
Add the running wattage for the appliances and equipment that could reasonably operate at the same time. A home powering refrigeration, lights, electronics, and a few outlets will have very different requirements from one that also wants central air conditioning, an electric range, water heating, or pool equipment available.
Manufacturer information is more useful than generic appliance charts when exact specifications are available.
3. Account for Starting Demand
Some appliances and HVAC components need additional power for a short period when they start. This is especially important for motor-driven equipment, where startup demand can be significantly higher than normal operating demand.
Equipment that may have a higher starting load includes air conditioners, heat pumps, refrigerators, freezers, well pumps, sump pumps, garage door openers, and certain power tools. Because startup requirements vary widely by equipment, use manufacturer specifications whenever possible rather than applying a single universal multiplier. A generator needs enough available capacity to support the loads already running while also handling the applicable startup demand when another piece of equipment turns on.
4. Factor in Heating and Cooling
HVAC equipment is often one of the biggest considerations when sizing a generator for a Texas home. If keeping the air conditioner running during a summer outage is a priority, include the AC system’s electrical requirements from the start rather than adding them after everything else has been calculated.
Heating can matter just as much during colder weather. Homes with electric heating equipment or a heat pump may have different backup-power requirements than homes with gas-fired heating. If a heat pump system uses electric auxiliary or backup heat, that equipment can add substantial demand, so the specific HVAC setup needs to be considered as part of the load assessment.
5. Consider the Home’s Electrical Setup
Square footage provides context, but it doesn’t tell you how much power a house needs during an outage. A 2,000-square-foot home with gas appliances and one smaller AC system may need substantially less backup capacity than another 2,000-square-foot home with electric water heating, multiple HVAC systems, a well pump, and other large loads.
The existing electrical infrastructure also matters. Before a standby generator and transfer equipment are installed, an electrician should evaluate the electrical service and electrical panel to determine how the new equipment will integrate with the home and which loads will be supported.
Whole-Home vs. Essential-Load Backup
One of the biggest decisions is whether you want backup power for selected essentials or a much larger portion of the home. Essential-load backup focuses on the equipment you consider necessary during an outage, such as refrigeration, lighting, internet equipment, medical devices, pumps, and selected outlets. Limiting supported loads can reduce the required generator capacity.
A broader or whole-home setup may include HVAC equipment, kitchen appliances, water heating, and additional circuits. Even then, “whole-home” does not necessarily mean every electrical load should operate simultaneously. Generator capacity, transfer equipment, household demand, and any load-management controls should be designed to work together.
Why a Load Assessment Matters
Online generator charts often pair a certain generator size with a certain home size, but that approach leaves out the biggest factor: how the household actually uses electricity. A load assessment looks at the equipment you want backed up, its running demand, applicable startup requirements, and which loads may operate at the same time.
It also lets you decide where you are willing to compromise. You may decide that keeping the AC, refrigerator, lights, and a few outlets running matters more than powering every appliance in the house. Another homeowner may want a larger standby setup that requires very little adjustment during an outage. The right generator is the one designed around those priorities.
Get the Right Generator Size for Your Home
Generator sizing depends on more than square footage. The right setup depends on what you want to keep running during an outage, how much power those loads require, and how the generator will connect to your home’s electrical system.
Blue Ribbon Cooling, Heating, Plumbing, & Electrical can evaluate your home, review your priority loads, and help determine the generator capacity and setup that best fit your needs. Schedule a generator consultation with Blue Ribbon to get a recommendation based on your home and the equipment you actually want to power.