Size is the single most important decision in a standby generator install. Too small and it trips offline the moment your AC kicks on during a storm — exactly when you need it. Too large and you’ve paid for capacity you’ll never use. Here’s how sizing actually works, and why South Louisiana changes the calculation.
Generators are sized in kilowatts (kW)
A standby generator’s output is rated in kilowatts. A typical air-cooled home unit runs from around 14 kW up to about 26 kW; larger liquid-cooled units start near 27 kW and climb from there. But the headline number only matters in relation to what you’re trying to run — and to the surge your appliances draw when they start.
Two ways to size: whole-home vs. managed
There are two philosophies, and the right one depends on your budget and your must-haves:
- Whole-home — a unit large enough to run essentially everything at once, including central air. Simplest to live with; you barely notice the grid is down.
- Managed / essential circuits — a smaller unit paired with smart load management that runs your critical circuits and sheds lower-priority loads on the fly. This lets a modestly sized generator power more of your home than its raw kW rating suggests — often the best value.
The South Louisiana wildcard: air conditioning
Here’s what makes sizing different in our climate. Air conditioning is non-negotiable through a summer outage — and an AC compressor draws a large surge of power at the instant it starts, several times its running draw. Size only for “running” loads and your generator can stall when the compressor cycles on in the middle of the night.
A good install accounts for that startup surge (and for multiple AC systems in larger homes). It’s the number-one reason sizing here should be a real calculation, not a rule of thumb. The hub page has a quick overview of the typical tiers if you want the short version.
The typical tiers
- ≈ 14–18 kW (managed essentials) — fridge, well pump, a zone of AC, lights, internet, medical equipment.
- ≈ 22–26 kW (whole-home) — the most popular choice in South Louisiana: central AC plus the rest of the house.
- 27 kW and up (large / liquid-cooled) — larger homes, multiple AC systems, long-runtime needs.
How a pro actually sizes it
A qualified installer doesn’t guess. They perform a load calculation: inventorying your major appliances, measuring or estimating the running and starting loads, factoring your AC’s locked-rotor surge, and confirming your fuel supply can feed the unit. Natural gas, for instance, slightly de-rates a generator compared to propane, which also affects the size you need (more in the fuel guide).
This is part of the free in-home assessment we connect you with — whether you’re in New Orleans, Baton Rouge, Lafayette, or anywhere in the service area.
Don’t oversize
It’s tempting to “round up to be safe,” but an oversized generator costs more upfront, burns more fuel, and can actually run less efficiently under light loads. The goal isn’t the biggest unit — it’s the right unit, sized to your home and your priorities.
Next steps
- See how it gets installed: What to Expect on Generator Install Day
- Pick your fuel: Natural Gas vs Propane
- Want a real load calculation? We’ll connect you with a local installer for a free assessment — start with your city.