What Size Generator Do You Actually Need for Your Texas Home?
"What size generator do I need" has a fast, rough answer and a precise, better answer. Our sizing calculator gives you the precise version in about a minute. This guide explains the reasoning so the number it gives you actually makes sense.
The fast answer, by home size
| Home size | Typical kW range | What that covers |
|---|---|---|
| Under 1,800 sq ft | 10–14 kW | Essentials — fridge, lights, outlets, a well pump, one AC zone or furnace fan |
| 1,800–2,800 sq ft | 14–18 kW | Most of the home — one central AC, kitchen, water heater on rotation |
| 2,800–4,000 sq ft | 18–24 kW | Whole home — a larger single AC or two smaller units, everything running |
| 4,000+ sq ft | 24–32 kW | Large home — multiple AC systems, pool equipment, workshop loads |
These bands work for a typical home. Yours might not be typical — which is exactly why the two mistakes below happen.
Mistake 1: sizing by square footage alone
Square footage is a decent proxy for "how much AC do you probably have," but two 2,400 sq ft homes can have wildly different actual loads. A single-story house with one 4-ton AC unit needs less generator than a two-story with two AC zones, an electric water heater, and a well pump — same square footage, different answer. If your home has above-average electrical loads (electric everything, a pool, a shop), size by the loads you actually want covered, not just the floor plan.
Mistake 2: ignoring motor starting surge
The number on an AC unit's nameplate is its running watts. When it starts, it briefly draws 2–3× that — for a fraction of a second, but a generator has to be able to supply it or the breaker trips (or worse, the unit doesn't start at all). A 5-ton AC compressor might run at 6,000 watts but surge to 10,000+ watts on startup. If you're sizing by adding up appliance wattages yourself instead of using the calculator, always check the surge/LRA (locked rotor amps) rating, not just running watts — this is the single most common reason a "correctly sized" DIY calculation still trips under real conditions.
When to size up from the chart
- You have two or more AC systems that could both call for cooling at once.
- You have a well pump — these have a meaningful surge draw and often get left off DIY calculations.
- You want an EV charger to work during an outage — Level 2 charging is a substantial, continuous load on top of everything else.
- Someone in the home depends on powered medical equipment — build in margin, don't size to the exact minimum.
When it's fine to size down
If your real goal is "keep the fridge cold and the lights on," not "run the house exactly like normal," an essentials-tier unit is a legitimately smaller and cheaper answer — and for many households, the honest one. Bigger isn't automatically better; it's more expensive to buy and to fuel.