How Many Watts Does a CPAP Use? Typical Draw, Humidifier and Backup Power
By Seamless Home Team, Home services operations · November 3, 2026 · Updated November 3, 2026
Quick answer
A CPAP uses far less power than most household appliances, and a heated humidifier and heated tubing add to what the blower draws. As one manufacturer example, ResMed's AirSense 11 user guide lists a typical power consumption of 56.1 watts and a peak of 73.2 watts, through a 65-watt power supply. Your machine's figures are in its user guide and on the power supply label, and they differ by model and settings. For energy, multiply watts by hours of use: 56.1 watts for 8 hours is about 450 watt-hours, or 0.45 kWh. Turning the humidifier and heated tube down or off lowers the draw, which matters most when running from a battery. Talk to your prescribing provider before changing therapy settings.
A CPAP machine is a small electrical load. It is also one of the few loads in a house that has to run all night, every night, and the one people most often ask about when the power goes out. The number to start with is in the machine's user guide.
As an example, ResMed's AirSense 11 user guide lists a typical power consumption of 56.1 watts and a peak of 73.2 watts, through a 65-watt power supply. That is a small fraction of what a microwave or a space heater draws.
Where a CPAP's watts go
A CPAP has three parts that use electricity:
| Part | What it does |
|---|---|
| Blower and controls | Moves air at the prescribed pressure, runs the screen and connectivity |
| Heated humidifier | Warms water in the tub so the air is not dry |
| Heated tubing | Keeps the air warm along the hose to reduce condensation |
That is why the same machine can draw noticeably different amounts from one night to the next. A cold bedroom, a high humidity setting or heated tubing set warm all push the figure up toward the peak. Running with the side cover instead of the water tub, or with the heated tube off, brings it down. Settings are part of your therapy, so talk to your prescribing provider before changing them.
Find the number for your machine
Look in three places:
- The user guide. The technical specifications section usually lists the power supply rating and, for many current machines, typical and peak power consumption.
- The power supply label. It gives the output in volts and amps. The AirSense 11's supply, for example, is rated 24 V DC at 2.71 A, which is about 65 watts. Treat that as the most the supply can deliver, not what the machine uses on a typical night.
- The device label. It confirms the input voltage the machine expects.
Different brands, models and generations have different figures, so do not assume another machine matches the AirSense 11.
Watt-hours per night: watts × hours
Energy is power over time:
watt-hours = watts × hours, and kWh = watt-hours ÷ 1,000
Arithmetic illustrations using ResMed's published AirSense 11 figures, not measurements of your night:
- 56.1 W typical for 8 hours: about 450 Wh (0.45 kWh)
- 73.2 W peak for 8 hours: about 586 Wh, an upper bound for planning
- 56.1 W typical for 6 hours: about 337 Wh
The watts to kWh calculator does this for any wattage and number of hours. To compare a night's use against a battery rated in amp-hours, the watt-hours to amp-hours calculator converts between the two.
Running cost
Multiply kWh by the price on your bill. As an illustration at 16 cents per kWh, 0.45 kWh a night costs about 7 cents, or roughly $2.20 for 30 nights. A CPAP is not what makes an electricity bill high. Because it runs overnight, it also tends to run in the cheaper hours on a time-of-use rate.
A CPAP in a power outage
This is where the small number matters. ResMed's guide notes that if power is interrupted during therapy, the AirSense 11 restarts automatically when power returns. That is useful after a flicker. It does not help during an outage that lasts the night, or several nights.
Options fall into three groups:
- A manufacturer's battery or DC accessory. Many CPAP makers sell their own battery packs or DC power cords. ResMed lists an Air11 DC/DC converter among the AirSense 11's accessories. Use only the power accessories the manufacturer approves.
- A portable power station. These plug in like a wall outlet. The power station's watt-hour rating, less conversion losses, has to cover your night with the settings you actually use.
- A home battery on a critical load panel. A whole-home battery treats a CPAP as one of its smallest loads. If the bedroom circuit is on the backed-up panel, the machine keeps running without anyone getting up to switch anything over, alongside the refrigerator, lights, internet and a sump or well pump.
Whichever route you choose, size for the peak figure and your real settings, not the typical figure alone. Test it on a normal night before you rely on it. If you depend on the machine medically, tell your utility and your provider, and keep a plan for a longer outage.
Planning backup circuits
A home battery project starts with a list of what must stay on. A CPAP is usually near the top, together with refrigeration, heating controls and anything else medical. A critical load panel is how those circuits are separated from the rest of the house, and the critical load panel planner checks whether a battery can carry the circuits you pick. For the next-biggest overnight load on most lists, see how many watts a refrigerator uses.
Home battery and backup projects that Seamless Home coordinates begin with that list. Get a free estimate to start. Coverage is confirmed per service area rather than promised as blanket availability.
Frequently asked questions
How many watts does a CPAP use?
It depends on the model and settings. As an example, ResMed's AirSense 11 user guide lists typical power consumption of 56.1 watts and peak consumption of 73.2 watts, using a 65-watt power supply. Check your own machine's user guide or power supply label.
How many watt-hours does a CPAP use per night?
Watts × hours. At the AirSense 11's typical 56.1 watts, an 8-hour night is about 450 watt-hours (0.45 kWh); at its 73.2-watt peak for the whole night, about 586 watt-hours. Those are arithmetic illustrations, not measurements.
Does the humidifier add to a CPAP's power use?
Yes. A heated humidifier warms water and heated tubing warms the hose, both on top of what the blower uses. ResMed does not break its AirSense 11 figures down by part, so use the peak figure when planning backup. Running with heat turned down or off uses less, but it can change comfort, so ask your provider first.
How much does it cost to run a CPAP?
Multiply kWh by your electricity rate. As an illustration, 0.45 kWh a night at 16 cents per kWh is about 7 cents a night, or roughly $2.20 over a 30-night month.
Will a CPAP restart after a power outage?
Many do. ResMed's AirSense 11 user guide says that if power is interrupted during therapy, the device automatically restarts therapy when power is restored. That does nothing for the hours the power is out, which is what backup power is for.
Can a home battery run a CPAP?
Yes. A CPAP is one of the smallest loads a whole-home battery carries. Put the bedroom circuit on the backed-up panel so the machine runs through an outage along with the refrigerator, lights and internet.
Can I run a CPAP from a 12-volt battery?
Some machines support DC power through a manufacturer's converter. ResMed lists an Air11 DC/DC converter as an accessory for the AirSense 11. Use only the manufacturer's approved power accessories.