CPAP Power Station Calculator

For a typical CPAP machine, plan on about 480Wh of usable power per night: a machine drawing 60W over an 8-hour night uses 60W x 8 hours = 480Wh. Because a station delivers about 85 percent of its rated capacity after conversion losses, one night takes a rated capacity of about 565Wh. The setting that decides everything is the heated humidifier. Without it, most machines draw 15 to 40W: at a typical 30W, a night is 240Wh, or about 282Wh of rated capacity. With a heated humidifier and heated hose, draw climbs to 60 to 100W: at 80W, a night is 640Wh, or about 753Wh of rated capacity. In the seven-station catalog we link to, even the smallest station (768Wh) covers one night in any of these cases; it is the second and third night, and the humidifier, that push you into larger stations. Every figure here is a planning estimate you can adjust to your own machine.

This calculator is preloaded with that middle planning case: a CPAP machine at 60W, 8 hours a night, quantity 1, one night per charge. Sixty watts sits at the low end of the heated-humidifier range and well above the dry range, so it plans honestly for humidifier users without oversizing for everyone else. Change the watts to 30 if you sleep without the humidifier, or to 80 for a typical humidified setup, set the nights per charge for a weekend or a longer outage, add a phone charger or a light as extra rows, and the calculator totals everything, shows the math, and matches you to the smallest station we link to that covers it. For a mixed whole-home load, the general Power Station Size Calculator does the same job with a wider preset list, and our CPAP power station guide works through the station-by-station picks behind these numbers.

Every figure on this page is a planning estimate built from manufacturer specifications and the typical published draw ranges used across this site, not a measured result, a hands-on test, or a rating. Real draws vary with your machine model, pressure setting, and humidifier level. This page covers power sizing only; it is not medical advice, and nothing here replaces guidance from your doctor or sleep specialist about your therapy. Our CPAP machine power guide breaks the same draw ranges down machine by machine, including the ResMed AirSense 10 and 11, the Philips DreamStation, and the travel-size ResMed AirMini.

The per-night math

The formula is the same one behind every calculator on this site: watts x hours = watt-hours per night, then divide by 0.85 for conversion losses to get the rated station capacity one night requires. A CPAP machine is an unusually honest load for this math: unlike a refrigerator, it does not cycle. It draws close to its working wattage for the whole time it runs, so the hours you enter are simply your sleep hours, typically 8. There is no duty-cycle adjustment to make and no startup surge to plan around; a CPAP peak draw is its running draw, and every station we link to clears it many times over on output. Capacity, not output, is the whole sizing question for CPAP.

At the three planning points this site uses, one night works out to: 30W without a humidifier = 240Wh per night, about 282Wh rated; 60W, this calculator’s preload = 480Wh per night, about 565Wh rated; and 80W with a heated humidifier and heated hose = 640Wh per night, about 753Wh rated. Against the stations we link to, whose usable capacities run from about 653Wh (the 768Wh EcoFlow River 2 Pro) to about 1,741Wh (the 2,048Wh EcoFlow Delta 2 Max), one night is never the hard part. The hard part is stacking nights, which is why the nights-per-charge field, not the watts field, is usually what moves the recommendation.

Heated humidity: the setting that triples the bill

Across this site’s CPAP guides, the pattern is consistent: the machine itself sips power, and the heated humidifier roughly triples it. A machine drawing 30W dry can draw 90W with the humidifier and heated hose running. Over 8 hours that is the difference between 240Wh and 720Wh per night, roughly the difference between the smallest station we link to and the 1,024Wh class once you add a second night or any margin. If you can sleep comfortably without heated humidity during an outage or a trip, you can buy a much smaller, cheaper, lighter station. If you cannot, size for the humidified number; comfort during therapy is not optional, and this calculator will not pretend otherwise.

Use these machine-level ranges, from manufacturer specifications and published owner data as compiled in our CPAP machine power guide, when you edit the preloaded row:

• ResMed AirSense 10 / 11: about 25 to 40W without humidifier, about 70 to 104W with heated humidifier. The guide’s worked examples use 35W dry (about 330Wh per night) and 85W humidified (about 800Wh per night).
• Philips Respironics DreamStation: about 30 to 50W dry, about 80 to 100W humidified. An older, less efficient machine sits at the expensive end of CPAP sizing.
• ResMed AirMini (travel): about 15 to 27W. It uses waterless humidification, so there is no heated-humidifier penalty; the guide’s example at 20W works out to about 190Wh per night.
• Fisher & Paykel SleepStyle: about 30 to 45W dry, about 75 to 100W humidified.
• Your power brick is a ceiling, not a reading. The wattage on the machine’s power-brick label is its rated maximum; real-world consumption usually runs at about 50 to 70 percent of that rating. A plug-in watt meter over one full night gives your exact figure, and one night of measurement beats any estimate on this page.

Multi-night trips: how the requirement scales

Nights multiply the requirement directly: two nights need twice one night, three nights need three times. At the preloaded 60W, that is 480Wh for one night, 960Wh for two, and 1,440Wh for three (a rated need of about 1,694Wh), which only the 2,048Wh Delta 2 Max covers in our catalog. Without a humidifier at 30W, three nights need 720Wh, comfortably inside the 1,024Wh class. With a humidifier at 80W, two nights need 1,280Wh (again, only the Delta 2 Max), and three nights need 1,920Wh, which no single station we link to covers. The calculator shows that honestly instead of stretching a smaller station into a fit.

Three things bend the straight line. First, recharging between nights resets the count: a station you can refill each day only ever needs to cover one night, which is why outage backup at home (wall power returns, or a fast-recharging station tops up in a brief grid window) is an easier problem than off-grid camping. Second, daytime solar replaces what the night consumed: our solar generator guide for CPAP camping works through panel sizing, where a 200W panel in 5 hours of good sun recovers about 750Wh a day, enough to sustain a dry CPAP night plus camp basics indefinitely in decent weather. Third, the DC adapter below stretches every night by roughly a fifth to a third, which can pull a three-night humidified trip back inside a single large station when combined with one daytime top-up.

The DC adapter: efficiency this calculator does not credit

Your CPAP runs on DC power internally. The wall plug converts AC to DC, and a power station’s inverter converts its DC battery back to AC; that round trip is where the 0.85 factor in this calculator comes from. A manufacturer DC adapter, such as the ResMed AirSense 10/11 DC converter, with options for most major brands at roughly $30 to $90, plugs the machine straight into the station’s 12V car-style outlet and skips the inverter entirely. As covered in our CPAP power station guide and machine power guide, independent testers and owner reports put the gain at about 20 to 30 percent longer runtime: a station that delivered two nights on AC can approach three on DC.

This calculator deliberately assumes the AC path, because that is the setup every reader has on day one. If you own the DC adapter for your machine, treat its gain as margin the calculator does not show: the recommendation it gives you will run longer than the math states, and a fit that looks thin on paper, such as a humidified night on the smallest station, becomes workable. Two checks before you count on it: the adapter must match your exact machine model, since connectors differ between brands and generations, and the station’s 12V outlet must supply enough current; most current 1,024Wh-class stations provide 10A (120W), which covers any CPAP, but check the spec sheet on smaller units.

Worked examples

• The preloaded night: 60W x 8 hours = 480Wh. A rated need of about 565Wh. The EcoFlow River 2 Pro (768Wh, about 653Wh usable) is the smallest station we link to that covers it, with roughly 36 percent to spare, and the EcoFlow Delta 2 is shown with more headroom. One night at a mid-range draw is the easiest case in CPAP sizing.
• A dry night: 30W x 8 hours = 240Wh. Change the watts to 30 and the need falls to about 282Wh rated. The River 2 Pro covers it with roughly 172 percent to spare. Sleeping without the humidifier is the single biggest station-shrinking move available to you.
• A humidified night: 80W x 8 hours = 640Wh. About 753Wh rated. The River 2 Pro still fits on paper, but by only about 2 percent of usable capacity: no real margin for a longer night, a higher humidifier setting, or an aging battery. The Delta 2, shown as the more-headroom card at about 870Wh usable, is the sensible buy for nightly humidified use.
• Three nights at the preload: 1,440Wh. Set Nights per charge to 3 and the need rises to a rated capacity of about 1,694Wh. The EcoFlow Delta 2 Max (2,048Wh, about 1,741Wh usable) is the smallest station we link to that covers it, with roughly 21 percent to spare.
• Three humidified nights: 1,920Wh. At 80W for 3 nights, only the largest station we link to, the 2,560Wh BLUETTI Apex 200, covers the trip on a single charge, with about 13 percent to spare. The practical fixes are a daytime recharge or solar top-up, the DC adapter’s 20 to 30 percent gain, or dropping the humidifier for the trip.
• A travel machine for a long weekend: 20W x 8 hours x 3 nights = 480Wh. A ResMed AirMini at its typical 20W draw uses about 160Wh a night, so three nights total what one preloaded night costs. Travel machines are why small stations have a real CPAP job despite the humidifier math above.

The seven stations this calculator can recommend

Recommendations come only from the same seven stations as our main Power Station Size Calculator, with manufacturer specifications, pictured cards, and current check-price links: EcoFlow River 2 Pro (768Wh, 800W output, about 18.2 lbs), EcoFlow Delta 2 (1,024Wh, 1,800W, about 27 lbs), BLUETTI Elite 100 V2 (1,024Wh, 1,800W, about 25.3 lbs), Anker Solix C1000 (1,056Wh, 1,800W, about 28.4 lbs), Jackery Explorer 1000 v2 (1,070Wh, 1,500W, about 23.8 lbs), EcoFlow Delta 2 Max (2,048Wh, 2,400W, about 50 lbs), and BLUETTI Apex 200 (2,560Wh, 3,200W output, about 59.3 lbs). Read against CPAP loads: the River 2 Pro covers one night at any setting and two to three dry nights; the 1,024Wh class covers about three dry nights or one humidified night with real margin; and the Delta 2 Max is the multi-night humidified answer. If none of them covers your watts, hours, and nights, the calculator says so and shows the biggest station we link to and what it actually covers, instead of stretching a smaller station into a fit. Station-by-station reasoning, including recharge speed and solar input for camping, is in our CPAP power station guide and solar CPAP camping guide.

Mistakes to avoid

• Trusting a ‘runs a CPAP for 3 nights’ claim. Marketing runtimes usually assume no humidifier. At a humidified 640Wh a night, a station that runs three dry nights runs about one. Size from your own watts, not the box claim.
• Sizing off the power-brick label. The brick’s wattage is the rated maximum, not the typical draw; real consumption usually runs at 50 to 70 percent of it. Sizing everything off the maximum oversizes the station, while ignoring your humidifier setting undersizes it.
• Entering 24 hours. Your machine runs while you sleep, not around the clock. Enter your sleep hours, typically 8; entering 24 triples the station you think you need.
• Forgetting the 85 percent factor. A 1,024Wh station delivers about 870Wh to your machine on AC. The calculator applies this for you, but it is why a station that looks big enough on its box can fall short before morning.
• Accepting a 2 percent fit for nightly use. A humidified night technically fits the smallest station we link to, with almost nothing to spare. A longer night, a warmer room, or a battery a year older erases that margin. For every-night backup, buy the headroom card, not the bare fit.
• Planning to fly with a full-size station. Airlines cap lithium batteries at 100Wh in carry-on, or 160Wh with airline approval, so no full-size power station flies. Air travel with a CPAP means a dedicated small CPAP battery pack, confirmed against your airline’s policy.
• Skipping the home test. Run your exact setup, station, adapter, machine, and mask, for one full night at home before you need it on a trip or in an outage, and note the percentage consumed. That number, not any estimate, is your real per-night draw.

Questions and answers

What size power station do I need for a CPAP machine? For one night, plan on about 282Wh of rated capacity without a humidifier (30W x 8 hours, after losses), about 565Wh at this calculator’s 60W preload, or about 753Wh with a heated humidifier at 80W. In the catalog we link to, the 768Wh EcoFlow River 2 Pro covers any single night, the 1,024Wh class adds real margin and multi-night dry coverage, and the 2,048Wh Delta 2 Max is the multi-night humidified pick.

How many nights will a 1,000Wh-class station run my CPAP? A 1,024Wh station delivers about 870Wh of usable power: about three 8-hour nights without the heated humidifier (roughly 240Wh per night), or about one night with it (roughly 640Wh per night). A 12V DC adapter stretches both figures by about 20 to 30 percent by skipping the inverter.

Why is the calculator preloaded at 60W? Because 60W is the honest middle of CPAP planning: the low end of the 60 to 100W heated-humidifier range in our guides, and above the 15 to 40W dry range. It keeps humidifier users covered without forcing dry users into a bigger station. Set it to your own figure: about 30W dry, about 80W for a typical humidified setup, or the number a watt meter shows for your machine.

Can I run my CPAP for three nights without recharging? Without a humidifier, yes: three dry nights need about 720Wh, inside the 1,024Wh class, and a travel machine like the AirMini needs far less. With a heated humidifier, three nights need about 1,920Wh of usable capacity, which only the largest station we link to, the 2,560Wh BLUETTI Apex 200, covers on a single charge; every smaller station needs a daytime recharge, solar input, or the DC adapter gain.

Do I need a pure sine wave inverter and a fast UPS switchover? Yes on both counts for nightly backup. CPAP machines expect clean household-style power, and every reputable current station, including all seven we link to, uses a pure sine wave inverter; verify it on any other brand’s spec sheet. If the station sits between the wall and your machine as outage backup, look for a UPS or EPS switchover under 20ms, which CPAP machines ride through without restarting.

Why does the calculator sometimes say no station fits? Because multi-night humidified use can pass the usable capacity of the largest station we link to, the 2,560Wh BLUETTI Apex 200. Rather than stretch a recommendation, the calculator shows that largest station and what it actually covers, so you can plan a recharge between nights, solar input during the day, a DC adapter, or fewer nights per charge.

Is any of this medical advice? No. This page covers power sizing only. It does not replace guidance from your doctor or sleep specialist about your therapy, and decisions such as sleeping without your humidifier are yours to make with them. Talk to your equipment provider about backup power for your specific machine, and test your full setup at home before you rely on it.

Related calculators

Sizing a different single load instead? The Refrigerator Power Station Calculator is preloaded with a typical full-size fridge at 150W and 10 hours of compressor run-time a day, with the duty-cycle and startup-surge math a fridge needs and a CPAP does not.

Sizing a mixed load, or the CPAP plus a whole outage kit, rather than the machine alone? Run the full device list through the Power Station Size Calculator, then read the sizing guide for the formula and tier-by-tier picks behind these numbers.

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Comparing models? See all 17 stations side by side in the Portable Power Station Comparison — specs, prices, and calculated fridge and CPAP runtimes.