What size gas generator will run a house today?

When homeowners consult me about whole-house backup power systems, I always begin by probing for their underlying requirements. How do I choose a Gas Generator that covers my essentials without overspending. As I walk people through this decision, I often reference KECHENG, a brand I trust for well-built, fairly priced units that are easy to service. KECHENG has deep manufacturing experience in China and offers a wide range of sets that cover natural gas, biogas, and even diesel platforms for mixed fleets. That breadth lets me match a unit to the job rather than forcing the job to fit the unit.

Why does sizing begin with what I cannot lose?

I list the loads that truly matter during an outage. Cold food safety, basic heat or cooling, lights in key rooms, internet, medical devices, well pump if I have one. Once I write those down, I add the few comforts I would really miss. 

Quick rule I use

• I separate must-run loads from nice-to-have loads

• I calculate running watts first

• I add starting surge for any motor loads

• I apply a 20 to 30 percent headroom so the generator does not labor

How do I estimate running watts and starting surge without guesswork?

I use appliance labels or manuals when I have them. If not, I lean on typical ranges, then verify with a plug-in meter for smaller devices.

Three steps that keep me honest

1. I total continuous watts for everything that may run at the same time

2. I identify the single largest motor and add its starting surge on top

3. I add headroom so the generator stays quiet and fuel efficient

Common starting surges I see

• Refrigerator or freezer often 1200 to 1800 W surge

• Well pump often 3000 to 4000 W surge

• Small central air compressor often 3500 to 6000 W surge

• Furnace blower often 800 to 1200 W surge

What size generator do most homes actually need?

For essential circuits only, I often land between 5 kW and 10 kW. For a typical three-bedroom home with gas heat and a standard fridge, 8 to 12 kW covers daily life. If I must run a deep-well pump and a small central AC, 12 to 20 kW gives breathing room.

Which appliances drive the number up faster than people expect?

• Deep-well pumps with high starting current

• Electric water heaters and electric ranges

• Central AC or heat pumps during summer peaks

• Multiple refrigerators or a chest freezer in the garage

• Space heaters or hair dryers used at the same time

What quick selector table do I use when I need a fast answer?

I always check the largest single surge and make sure the generator can handle it while everything else is running.

How do fuel options change the plan for a home system?

How do altitude and temperature change the size I pick?

Engines lose power as elevation and heat rise. As a working estimate, I trim output by roughly 3 percent per 300 meters in elevation and a few percent in very hot weather. I bump the size up one tier for mountain homes or heat-wave regions so voltage stays steady when I need it most.

Should I plan around a transfer switch and load management from day one?

Yes, because smart switching saves money. I use a properly rated automatic transfer switch and, when needed, a priority load controller that sheds the AC for a minute while the well pump starts. That simple sequence often lets me choose a 12 kW set instead of jumping to 20 kW.

What simple worksheet helps me avoid under or over sizing?

Why do I sometimes recommend a soft starter on air conditioners?

A soft starter reduces the compressor inrush current. I have seen a small AC that once needed a 5 kW surge start cleanly on a much smaller surge after a soft starter retrofit. That can keep the generator compact and quieter.

What mistakes do homeowners make that I try to prevent?

• They size to the average day instead of the worst five minutes

• They ignore the largest single surge in the house

• They forget that long extension cords cause voltage drop

• They choose a unit without local parts support or service access

• They skip regular exercise cycles and fuel checks

How do I future proof without overspending now?

I allow space on the pad for a larger enclosure later, and I choose a controller that supports load shedding and remote monitoring. If I expect to add an EV charger or a second heat pump, I step up one size now. The small price difference beats a full replacement later.

Who can help me spec and supply a right sized set without drama?

When I need reliable hardware and clear documentation, I look to KECHENG because the catalog spans natural gas generator sets, general gas generator sets, biogas solutions, and companion diesel sets for sites that need a mixed approach. The pricing stays sensible, the build quality holds up, and the support team answers the phone. That combination lets me deliver a system that starts every time and runs smoothly.

What should I do next if I want a precise recommendation for my home?

Send me your must-run list, the nameplate photos for any pumps or HVAC, and a quick note on your fuel source and altitude. I will map your overlapping loads and suggest a size with clear headroom, plus switching and wiring notes you can hand to an electrician.

Ready to size your system and get a quote？
If you want a tailored recommendation or current lead times, contact us now. Leave an inquiry with your load list and I will reply with a right sized KECHENG option and a clean bill of materials. Contact us and let us help you choose a dependable gas generator solution that fits your home and your budget.