Bottom line: Most Florida households riding out a hurricane need 2,000–3,500W of portable generator (or a ~1kWh power station) to cover the essentials — fridge, phones, fan, lights, CPAP. Add a portable AC or microwave and you’re looking at 3,500–5,000W. You don’t need to power everything — you need to power the right things.
Buying too small means the generator trips when the fridge compressor kicks on. Buying too big means wasted money, wasted fuel, and a heavier machine. Here’s how to size it right.
Running Watts vs Starting Watts: The Key Concept
Every appliance has two numbers:
- Running watts: what it draws continuously (a fridge: ~150W)
- Starting watts (surge): the brief spike when motors and compressors kick on (that same fridge: ~800W for a few seconds)
Your generator must handle the running watts of everything on at once, plus the single largest starting surge. This is where most people go wrong — they add up running watts, buy exactly that size, and the generator overloads the first time the fridge cycles.
Common Appliance Wattages
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Full-size refrigerator | 150–200W | 800–1,200W |
| Chest freezer | 100–150W | 600–900W |
| Portable AC (8,000 BTU) | 900–1,200W | 1,800–2,500W |
| Window AC (5,000 BTU) | 450–550W | 1,200–1,800W |
| Microwave | 1,000–1,200W | 1,200W |
| Box fan | 75W | 150W |
| CPAP (no humidifier) | 40–60W | 60W |
| CPAP (with heated humidifier) | 90–120W | 120W |
| Phone charger | 10–20W | 20W |
| Laptop | 65W | 65W |
| Wi-Fi router | 10W | 10W |
| LED lights (several) | 20–40W | 40W |
| TV (55″) | 150W | 150W |
| Sump pump (1/3 HP) | 800W | 1,300–2,000W |
| Well pump (1/2 HP) | 1,000W | 2,000–3,000W |
| Electric water heater | 4,000W+ | 4,000W+ (don’t bother — too big for portable) |
These are typical ranges; check your appliance’s nameplate or manual for exact numbers.
The 5-Minute Sizing Method
Step 1: List what you’ll run simultaneously. Be honest — not everything at once.
Step 2: Add the running watts.
Step 3: Add the largest single starting-watt spike from your list.
Step 4: Add a 20% safety margin. (Generators last longer and run quieter below max load.)
Example — typical Florida hurricane kit:
– Fridge: 150W running
– 2 phones charging: 30W
– Box fan: 75W
– 3 LED lamps: 30W
– CPAP (no humidifier): 50W
– Wi-Fi router: 10W
Running total: 345W. Largest surge: fridge at ~1,000W. Total needed: 345 + 1,000 = 1,345W. With 20% margin: ~1,600W.
A 2,000W generator (or a 1,500–1,800W power station) handles this with room to spare.
Example — add a portable AC:
Same as above (345W) + 8,000 BTU portable AC (1,100W running, 2,200W surge). Running total: 1,445W. Largest surge: 2,200W. Total: 3,645W. With margin: ~4,400W → buy a 4,500W-class generator.
What Size for Common Scenarios
“Just the essentials” (fridge, phones, fan, lights, CPAP): 2,000W generator or 1kWh power station.
This is the sweet spot for most households. A 2,000W inverter generator is relatively quiet, sips fuel (~1 gallon per 8–10 hours at light load), and one person can carry it.
“Essentials + portable AC”: 3,500–4,500W generator.
Air conditioning is the big step up. In a Florida August outage, a single-room portable AC is the difference between miserable and tolerable — but it roughly triples your power requirement.
“Essentials + AC + microwave + sump pump”: 5,000–7,500W generator.
Now you’re in serious portable-generator territory — heavier, louder, thirstier. At this point, price out a manual transfer switch installation (a few hundred dollars by a licensed electrician) so you’re not running a spiderweb of extension cords.
“The whole house”: 10,000W+ or a standby generator.
That’s beyond portable — you’re looking at a permanently installed standby unit ($10,000–$15,000+ installed). For most people, that’s a “someday” project, not a hurricane-season purchase.
Power Station Sizing (Battery Units)
Power stations are sized by capacity (Wh) more than output, because runtime is the constraint:
- 500Wh class (~$300–$400): Phones, laptops, CPAP for a night or two, small fan. Won’t meaningfully run a fridge.
- 1,000Wh class (~$500–$800): The hurricane sweet spot — fridge for ~6 hours, CPAP all night, phones for days. See our Delta 2 vs Jackery 1000 v2 comparison.
- 2,000Wh+ class ($1,200+): Fridge for 12+ hours, or fridge + more loads. Heavy (45–60+ lbs) and pricey.
Rule of thumb: take the appliance’s running watts, multiply by the hours you need, divide by 0.85 (inverter efficiency). That’s the Wh you need. Fridge at 150W × 6 hours ÷ 0.85 ≈ 1,060Wh → a 1kWh unit.
Extension Cords and House Connections
Extension cords: Use heavy-duty outdoor-rated cords (12-gauge for runs over 50 feet or loads above 1,500W). Undersized cords overheat — a genuine fire risk. One appliance per cord when possible.
Connecting to your breaker panel: Requires a manual transfer switch or interlock kit installed by a licensed electrician. Never backfeed through a wall outlet (“suicide cord”) — it can kill lineworkers and it’s illegal. Budget a few hundred dollars for a proper interlock installation.
⚠️ Generator safety reminder: Gas generators produce deadly carbon monoxide. Outdoors only, at least 20 feet from your home, exhaust pointed away from windows and doors. Battery-powered CO alarms on every floor. If an alarm sounds — get out and call 911.
Frequently Asked Questions
Is it bad to run a generator at full load?
It’s hard on the engine, louder, and burns more fuel. Size so your typical load is 50–80% of the generator’s rated running watts. The 20% margin in our sizing method handles this.
Can I run my generator in the rain?
Generators need protection from direct rain (water + electricity + hot engine = bad), but never in an enclosed space — not a garage, not under a tarp tent against the house. Use a purpose-built generator tent/cover that keeps rain off while maintaining full airflow, positioned 20+ feet from the home.
How long can a portable generator run continuously?
Most are designed for 8–12 hours per tank, then refuel and check oil. For multi-day outages, shut down periodically to check oil level — low oil destroys small engines fast. Let it cool before refueling (gasoline + hot muffler = fire).
What about inverter vs conventional generators?
Inverter generators produce cleaner power (safe for laptops, phones, CPAP), run quieter, and adjust engine speed to the load (better fuel economy). They cost more per watt. For hurricane backup powering electronics, inverter is worth it. Conventional (open-frame) generators are cheaper and fine for fridges, tools, and lights.
Should I get dual-fuel (gasoline/propane)?
Propane never goes stale, so it’s ideal for a generator that sits 11 months a year. You lose ~10% power on propane. Given Florida’s long quiet stretches between storms, dual-fuel is worth the small premium for most buyers.