A CPAP uses about 7-10 watts with the humidifier off and about 22 watts with the heated humidifier on, rising to 34-44 W with a heated tube (ResMed test data). Power supplies are rated 65-90 W, but real draw is far lower.
- Running watts
- 22 WTypical; 7–44 W across models
- Starting watts
- NoneNo motor surge
- Per day
- 0.18 kWh8 h of use
- Current
- 0.2 AAt 120 V while running
Figures checked against DOE, ENERGY STAR and manufacturer data on . Your model's label is the final word.
Watts by model and setting
Most cpap machine models draw between 7 and 44 W while running; a typical one draws about 22 W. 22 W (with heated humidifier) x 8 hours = about 0.18 kWh a night; without humidification it is under 0.1 kWh.
- Heated humidifier: the biggest factor, roughly tripling draw
- Heated tubing (such as ClimateLine) adds another 10-20 W
- Pressure setting and bilevel (BiPAP/ASV) therapy draw more than standard CPAP
- Room temperature and humidity settings change how hard the heaters work
Running a CPAP machine on a generator or power station
- Generator: at least 22 running watts. A generator rated 1,000 W or more covers it with room to spare.
- Power station: continuous output of at least 22 W. Pure sine wave output is the safe choice for motors and electronics.
| Power station capacity | Estimated runtime |
|---|---|
| 500 Wh | 19.3 h |
| 1,000 Wh | 38.6 h |
| 2,000 Wh | 77.3 h |
| 3,000 Wh | 115.9 h |
Based on 22 W average draw and 85% usable capacity.
- CPAP is a high-priority load in an outage; a 300-500 Wh power station runs one for several nights with the humidifier off
- Turning off the humidifier and heated tube cuts consumption by about two-thirds and is the easiest way to stretch battery
- Using the manufacturer's DC cable or converter avoids inverter losses; if using AC, choose a pure sine wave power station
- If you depend on your CPAP or BiPAP medically, talk to your doctor and equipment supplier about a backup plan and register with your utility's medical-needs program if available. Run a gas generator outdoors only, at least 20 feet from doors, windows and vents.
Add it to the generator calculator
Questions people ask
How long will a power station run a CPAP?
Divide usable battery watt-hours by your CPAP's draw. At about 10 W with the humidifier off, a 500 Wh station lasts roughly 35-40 hours after inverter losses; with humidifier and heated tube (35-45 W) it lasts closer to 10 hours.
Does a CPAP need a pure sine wave inverter?
Manufacturers recommend their own DC cables or pure sine wave power for battery operation; modified sine wave inverters can damage or upset the power supply. A DC connection is the most efficient option.
How many watts does a ResMed AirSense use?
ResMed's test data for the AirSense 10 AutoSet shows about 7 W device only, 22 W with the humidifier and 34 W with humidifier plus ClimateLineAir heated tube. The AirSense 11 ships with a 65 W power supply, which is a maximum rating, not typical use.