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What size generator do I need to run a CPAP overnight?

Q: What size generator do I need to run a CPAP overnight?

Plan on at least 250 running watts and 250 watts of surge capacity. That covers 200W of running load plus the largest start-up surge, with 25% headroom.

Overnight medical and comfort loads are tiny — the real requirements are run-time, fuel efficiency, and quiet, not watts.

The load

CPAP machine — 60W running
Box fan — 100W running, 150W starting
Phone charger — 10W running
LED lights (per room) — 30W running

SIZING PLATE4 LOADS · +25% HEADROOM

Total running watts

200 W

Peak (largest start)

250 W

Buy at least

250 W rated

Look for ~250W running / 250W surge or better.

Field note: Turn off the CPAP's heated humidifier to cut its draw by two-thirds. For medical equipment, pair any generator with a battery backup so a stall or refuel gap never interrupts therapy, and verify draw against your unit's label.

Right size: Small inverter (1,800W / 2,200W surge)

Typical price $500-1,100 · e.g. Honda EU2200i, Champion 2500 dual-fuel, Predator 2000

Camping, tailgates, home office, CPAP and overnight essentials, one small appliance at a time. Quiet and light, but one large compressor surge can max it out.

See current prices on Amazon

One size up: Mid-size inverter (3,500W / 4,000W surge)

Typical price $600-1,400 · e.g. Champion 4250 open-frame inverter, Westinghouse iGen4500, Generac GP3500iO

RV 13,500 BTU AC (especially with soft-start), fridge + window AC, storm essentials for smaller homes. The sweet spot of quiet, portability, and real capacity for most first-time buyers.

See current prices on Amazon

Adjust for your setup

Different fridge? Bigger AC? Uncheck and re-check below — the plate recomputes live.

This site earns commissions from qualifying purchases made through links to Amazon and other retailers, at no extra cost to you. Wattage figures are typical estimates — actual draw varies by model. Always verify against your appliance's nameplate, and consult a licensed electrician for any panel or hardwired connections.