How Many Watts Does a CPAP Use? Wattage by Model, From the Spec Sheets
The power brick on your CPAP says 90W. The battery you're looking at says 500Wh. You divide: 5.5 hours, less after inverter loss. Not a full night. So you look at a bigger, heavier, more expensive station — for a machine that, on its manufacturer's own typical rating, draws a little more than half of what the brick says.
The brick's rating is the most-quoted CPAP wattage and the least useful one. Manufacturers publish two other numbers — typical and peak consumption — and those are the ones that size a battery and an inverter. This page collects them by model, straight from the user guides, and shows what each does to a night of runtime.
The one-line answer: on manufacturer typical ratings a CPAP draws 6–56W depending on model, peaks at 27–104W when a heated humidifier and tube are warming up, and the humidifier setting moves the number more than the choice of machine does.
CPAP Wattage by Model: The Manufacturer Figures
Every figure below is the manufacturer's published number from the device's user guide or the power supply's nameplate. We haven't measured any of them, and where a manufacturer publishes only a power-supply rating, the table says so rather than guessing.
| Machine | Power supply rating | Typical consumption | Peak consumption | Where the figure comes from |
|---|---|---|---|---|
| ResMed AirSense 10 (AutoSet, Elite, with HumidAir) | 90W (24V × 3.75A) | 53W (57VA) | 104W (108VA) | AirSense 10 user guide, technical specifications |
| ResMed AirSense 11 (AutoSet, Elite) | 65W (input 2.0A) | 56.1W (111.5VA) | 73.2W (137.6VA) | AirSense 11 user guide, technical specifications |
| ResMed AirMini (travel) | 20W (24V × 0.83A) | 6.3W | 27W | AirMini user guide; standby 1W |
| Philips DreamStation 2 (Auto, Advanced) | 65W (24V × 2.71A); input 100–240VAC, 2.0–1.0A | Not published | Not published | Philips user manual and power supply nameplate |
| React Health / 3B Luna G3 | 65W; input 2A max | Not published | Not published | Product specifications |
| ResMed Air10 / Air11 DC converter (12V or 24V input) | 90W max | — | — | ResMed converter specifications |
Two terms, in the sense the spec sheets use them: typical is the steady draw under normal therapy settings, and peak is the highest draw the device can pull — on paper, the moment a heated humidifier and heated tube are both coming up to temperature. Neither is an average over eight hours of sleep. Both are conservative design figures, which is what makes them useful for planning: a battery sized on the typical number has margin, and an inverter sized on the peak number will not trip.
The AirSense 11's odd-looking numbers are worth a sentence. Its typical draw is slightly higher than the AirSense 10's, but its peak is lower, and its power supply is smaller (65W vs 90W). ResMed doesn't explain the difference; the likeliest reading is a gentler heater warm-up on the newer humidifier. On paper the two machines need the same battery and the 11 gets by with a smaller inverter.
The Three Numbers on a CPAP, and Which One to Use
A CPAP comes with three wattages, and people routinely plan with the wrong one.
The power supply rating (65W, 90W). This is the most the brick can deliver, not what the machine draws. It has to cover the peak with margin, so it overstates a night by two to four times. Use it for exactly one thing: confirming a 12V DC converter or an inverter can supply at least that much.
Typical consumption (6.3W to 56.1W). The manufacturer's steady-state figure. This is the number for battery planning. It already includes a humidifier at a normal setting on the ResMed machines, which is why it is well above the "CPAP motor only" draw most people picture.
Peak consumption (27W to 104W). The number for inverter and port sizing. A power station's AC outlet or a 12V car port has to clear this figure or the machine browns out during humidifier warm-up. It's also why a 100W USB-C port isn't a CPAP port — see power station port wattage limits.
There is a fourth number the spec sheet can't give you: the measured overnight average, which is what your battery actually pays for. Users who put a plug-in meter on a modern auto-CPAP commonly report averages of 40–70% of the manufacturer's typical figure, because the humidifier heater cycles rather than running flat out. That's a range from the field, not a spec, and the last section covers how to get your own.
On the VA figures: volt-amps are apparent power, watts are real power, and the gap between them is the power factor of the supply. Size batteries in watt-hours using the watts column; the VA column matters only if you're sizing a UPS or an inverter that's rated in VA.
What Actually Sets the Draw
Ranked by how much each moves the number:
- The heated humidifier. The single largest load, larger than the blower on most machines. Turning it off is the difference between one night and two-plus on the same battery — the math is in why the humidifier is the battery killer.
- The heated tube. A second heater on top of the first, and the reason the peak figures sit so far above the typical ones.
- Pressure. Higher pressure means more blower work. Real, but a smaller effect than either heater — a few watts across the normal therapy range.
- Ramp, standby, and the display. Single-digit watts. The AirMini's published standby draw is 1W; the full-size machines are a few watts more.
For planning, this site uses bands rather than model figures, because the same machine spans all of them depending on settings: roughly 30–40W with the humidifier off, 55–70W with it on, and 70–85W with a heated tube on top. Those are planning bands built from manufacturer figures like the ones above, not measurements. The nights-per-station table on the CPAP runtime comparison is built on them.
From Watts to Watt-Hours to Nights
The arithmetic, in the form published on how we research:
- Usable capacity = rated Wh × 0.85 (inverter loss, applied once, on the capacity side)
- One night = watts × hours of sleep
- Nights per charge = usable ÷ one night, rounded down to the nearest half night
Worked on a 1024Wh station like the Anker SOLIX C1000 Gen 2 (currently $499.98) (usable 870Wh) over an 8-hour night:
| Setup | Watts used | One night | Nights per charge |
|---|---|---|---|
| AirMini, manufacturer typical | 6.3W | 50Wh | 17 |
| AirSense 10, manufacturer typical | 53W | 424Wh | 2 |
| AirSense 11, manufacturer typical | 56.1W | 449Wh | 1.5 |
| AirSense 10 at published peak, all night (worst case) | 104W | 832Wh | 1 |
The peak row is not a real night — no machine runs its heaters flat out for eight hours — but it is the floor: even the worst case clears one night on a 1000Wh-class station. On a 768Wh bundle like the EcoFlow River 2 Pro Solar Generator (currently $619.00) (usable 653Wh), the AirSense 10 typical row drops to 1.5 nights and the worst-case row to a half night. Run your own numbers, including the 12V DC case that skips the inverter loss, in the CPAP runtime calculator.
How to Find Your Machine's Real Number
Three steps, each better than the last:
- Read the brick. Output volts × amps is the supply rating (24V × 3.75A = 90W). It tells you the ceiling and what any DC converter has to deliver. It does not tell you the draw.
- Read the technical specifications page of the user guide. ResMed prints typical and peak consumption there for every Air10 and Air11 device. If your manufacturer doesn't publish one, you're down to the brick and a meter.
- Put a plug-in watt meter on it for a night. A Kill-A-Watt or equivalent (roughly $20–35) logs cumulative watt-hours; divide by hours slept and you have the average that every other number on this page is only approximating. Do it once with your normal settings and once with the humidifier off, and you have both ends of your own range.
The meter reading is the number to put into the calculator. Everything above it is for the night before you own one.
FAQ
How many watts does a CPAP use per night?
Multiply the draw by hours slept. At ResMed's typical figure of 53W for the AirSense 10, an 8-hour night is 424Wh; at the AirMini's 6.3W it's 50Wh. Add the 0.85 inverter factor on the battery side — a 500Wh power station delivers about 425Wh — and the AirSense 10 example lands at exactly one night, with nothing left. Measured overnight averages are usually lower than the typical figure because the humidifier heater cycles, which is why the nights-per-station table on this site uses planning bands rather than the peak.
Does a CPAP use a lot of electricity?
No. At 53W typical for 8 hours a night, a CPAP uses about 155kWh a year — roughly $25 at a 16¢/kWh residential rate, and a good deal less if your measured average is below the typical figure. It matters on a battery, not on a utility bill: the same 424Wh night that costs seven cents from the wall is most of a 500Wh power station.
How many watts does a CPAP with a humidifier use?
On the ResMed machines the manufacturer's typical figure already includes a humidifier at a normal setting: 53W on the AirSense 10, 56.1W on the AirSense 11. Peak draw with humidifier and heated tube warming is 104W and 73.2W respectively. Turn the humidifier off and the same machines fall into the 30–40W planning band, which roughly doubles nights per charge. The AirMini has no heated humidifier, which is most of why its typical draw is 6.3W.
How many amps does a CPAP draw on 12V?
Watts divided by volts. At the AirSense 10's typical 53W that's about 4.4A at 12V; at its 104W peak, about 8.7A. ResMed's Air10 and Air11 DC converters are rated for 90W, or 7.5A at 12V, and a 12V car port on a power station is usually rated 10A (120W), so both clear the typical draw with room and the peak with little. Running on DC also skips the inverter's 15% loss — the trade-offs are in CPAP on 12V DC vs the AC inverter.
What size inverter does a CPAP need?
Size the inverter on the peak figure with margin: for a full-size machine with a heated humidifier and tube, 150W continuous pure sine wave is the sensible floor, and any power station with an AC outlet clears it — even 300W-output units. Pure sine wave matters more than the wattage: CPAP blowers and power supplies are designed for it, and every power station this site recommends for CPAP use has it. The sizing question that trips people is not the inverter but the outlet: a 100W USB-C port cannot run an AirSense 10 at peak.
Can a 300Wh power bank run a CPAP all night?
With the humidifier off, usually; with it on, usually not. Usable capacity is 300Wh × 0.85 = 255Wh. At the 30–40W humidifier-off planning band an 8-hour night is 240–320Wh — marginal at the low end and short at the high end. At the AirSense 10's typical 53W a night is 424Wh, well past what 255Wh delivers. The AirMini at 6.3W typical is the exception: 50Wh a night, five nights on 255Wh. If a 300Wh-class unit is the budget, plan on humidifier off and a 12V DC converter, and check the arithmetic in the runtime calculator.
The Bottom Line
Plan the battery on the manufacturer's typical figure, size the inverter or port on the peak figure, ignore the brick rating for both, and put a meter on the machine once so you stop estimating. On those rules a 1000Wh-class station runs a full-size CPAP with humidifier for two nights and a travel machine for a fortnight; the picks that make that trade-off well are in the best power stations for CPAP guide, and the nights-per-station arithmetic for every unit this site tracks is in the runtime comparison table.