Sizing is where most generator decisions go sideways. Pick a unit that’s too small and it’ll trip and stall the first time your air handler kicks on; oversize it and you’ve paid for capacity you’ll never touch. Getting it right means understanding what your home actually draws, and in this climate that comes down to one thing more than any other: your air conditioning. Here’s how the sizing logic works, written plainly so you can follow along before a contractor ever quotes you. (We’re the resource that connects you with one vetted, licensed local installer — the actual load calculation is theirs to run.)
kW is the number that matters
Standby generators are rated in kilowatts (kW). A residential unit in the Panhandle typically lands somewhere between 14 kW and 26 kW, though larger homes can need more. That rating tells you how much electrical load the generator can carry at once — and the goal is to match it to either your whole house or to the specific circuits you most want to keep alive.
Two broad strategies exist, and the difference matters for both comfort and cost.
Whole-home vs. managed (load-shedding)
Whole-home backup sizes the generator to run essentially everything you’d run on a normal day — both AC systems, the whole kitchen, every outlet — all at the same time. It’s the simplest experience: an outage feels like nothing happened. It also means a bigger, pricier unit.
Managed (load-shedding) backup uses a smaller generator paired with a smart panel that prioritizes. Instead of powering everything simultaneously, the system juggles the big loads — it might briefly pause one AC compressor while the oven is on, then rebalance. You keep the whole house functional without paying for peak-everything capacity. For a lot of Panhandle homes, especially two-story houses around Destin and Fort Walton Beach with two AC zones, load management is the sweet spot: comfortable backup without buying the biggest unit on the lot.
Neither approach is “better” in the abstract — it depends on your home and your budget.
The deciding factor: AC startup surge
This is the part unique to hot climates, and it’s where DIY sizing usually fails.
An air conditioner doesn’t draw a steady, predictable amount of power. The moment the compressor starts, it pulls a brief inrush — a surge that can spike to several times its normal running draw for a split second. A generator has to swallow that surge without sagging, or it trips offline and your AC never comes on.
In the Panhandle, where AC runs hard for most of the year and many homes have two systems, that startup surge — not the steady-state load — is frequently the single largest demand the generator ever sees. Size to the running watts and ignore the surge, and you’ve bought a unit that fails exactly when you need cooling most. A good installer accounts for this directly, and increasingly homes use soft-start devices on the compressors to tame the spike and let a smaller generator do the job. Whether that’s worth it for you is exactly the kind of thing a real load calc reveals.
Fuel changes the number
Here’s a wrinkle people miss: the same generator doesn’t produce the same output on every fuel. Standby units in this region run on either natural gas or propane, and they generally make somewhat less usable power on natural gas than on propane — a de-rating of a few percent that varies by model.
So “a 22 kW generator” isn’t a fixed promise; its real delivered capacity depends on what you feed it. If your home is on the edge between two sizes, your fuel choice can tip the decision. That’s one reason sizing and fuel can’t be settled in isolation — work through them together using our natural gas vs. propane guide, and factor in which fuel even reaches your address.
Why a rule of thumb isn’t enough
You’ll find plenty of “1,500 sq ft = X kW” shortcuts online. Treat them as a rough sanity check, nothing more. Two houses of identical square footage can have wildly different electrical demands depending on:
- How many AC tons, and whether there are one or two systems
- Electric vs. gas water heating, cooking, and clothes drying
- A private well pump (common in rural Crestview-area properties) versus city water
- Pool pumps, EV chargers, workshop equipment
- Whether you want true whole-home backup or a managed setup
A genuine load calculation adds up your actual major appliances and circuits, applies the right surge factors, and accounts for fuel de-rating. It’s the difference between a generator that quietly carries your home through a week without power and one that nuisance-trips on a hot afternoon.
Estimate, then verify
To get yourself in the ballpark before talking to anyone, try our generator sizing calculator. It’s a planning aid — a way to understand roughly where your home falls and what questions to ask — not a final spec and definitely not a quote. The real number comes from an on-site evaluation, because nobody can see your panel, your AC tonnage, or your well pump through a web form.
Putting it together
The short version: figure out whether you want whole-home or managed backup, respect the AC startup surge as the load that usually drives the size, and remember that fuel choice nudges the final number. Then get a professional load calc rather than trusting a square-footage shortcut.
If you’re still earlier in the process, our guide on whether you need standby power at all is the right place to back up to. And when you want a properly sized recommendation for your specific home, we’ll connect you with the vetted local installer we partner with — they’ll do the on-site calc and stand behind the result.