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What size generator do I need?
In Texas, air conditioning decides this — not square footage. A 3,000 sq ft house with one AC system needs less generator than a 2,200 sq ft house with two. Answer six questions and you will get a kilowatt range and the models that fit it.
Your estimate
This is an estimate from typical load values, not a load calculation. The final specification comes from a licensed electrician measuring against your actual panel at the site survey — which is free, and which is the number we stand behind.
Models that fit
The first is the smallest unit that meets the estimate. The ones after it give you headroom, and headroom is worth paying for in a Texas summer — a generator running at 95% of capacity in August has nothing left when a compressor kicks in.
Worth knowing: on natural gas the air-cooled range stops at 18kW. Above that the next step is a liquid-cooled unit at roughly three times the equipment price. If your estimate has landed just over the line, a soft-start on the largest air conditioner or a load management module usually brings it back under — and both cost far less than moving up a range. That is exactly the sort of thing the survey sorts out.
Want this confirmed against your panel?
The site survey is free and it is the only way to get a real installation number.
Why air conditioning drives the number in Texas
A generator has to survive the moment a compressor starts, not just the steady load once it is running. An air conditioning compressor draws several times its running current for the first fraction of a second — locked rotor amps — and if the generator cannot cover that surge, the voltage sags, the compressor stalls, and eventually something expensive fails.
That is why a house with two 4-ton systems can need more generator than a much larger house with one. It is also why soft-start modules and load management matter so much here: both attack the surge rather than the steady draw, and both are usually cheaper than moving up a generator size.
What the calculator assumes
- About 5kW of base household load — refrigeration, lighting, outlets, networking, garage doors.
- Roughly 1.2kW of running load per ton of air conditioning, plus a starting allowance on the largest system.
- Standard nameplate values for electric range, dryer, water heater and EV charging.
- With managed load, the second and subsequent AC systems are staged rather than started simultaneously.
What it cannot know
Your actual panel capacity, how your circuits are grouped, whether your gas meter can carry the additional demand, and what your city requires. Those come out of the survey, and any of them can change the recommendation. Treat this as a starting range, which is exactly how we treat it internally.