CPAP Runtime Calculator
Estimate how many hours or nights a battery or power station can run a CPAP machine during a power outage or while traveling.
Choosing a mode fills in a typical wattage above — check your specific machine's label or manual for its exact draw, since this varies by model and pressure setting.
Total runtime
8.5 hours
Nights of backup
1.1
This is a planning estimate only, not medical guidance. If you depend on CPAP therapy nightly, test your exact machine and battery combination in advance rather than assuming these figures during a real outage, and talk to your durable medical equipment provider or physician about a backup power plan that fits your specific prescription and equipment.
How the CPAP Runtime Calculator works
Enter your battery or power station's watt-hour capacity, choose whether your CPAP's heated humidifier is typically on or off (which fills in a typical wattage), and set your usual hours of sleep per night — the calculator estimates total runtime hours and how many nights of backup that provides.
As with the other power-station tools here, the estimate applies a typical 85% usable-efficiency factor to account for inverter and battery losses between the battery's rated capacity and what your CPAP actually receives.
Frequently asked questions
Why does using a heated humidifier roughly double the power draw?
A CPAP's motor and electronics alone draw relatively little power, typically in the range of about 7-30 watts depending on the model — a heated humidifier adds a separate heating element that draws meaningfully more power on top of that, which is why enabling it can roughly double the machine's total wattage.
Can I trust this estimate to plan for an actual power outage?
Use it as a starting point only, not a guarantee — as covered in the disclaimer above, test your specific CPAP machine and battery combination in advance, since actual wattage varies by model, pressure setting, and mask type, and a real test removes that uncertainty before you actually need the backup power.
Is a heated humidifier worth disabling to extend battery runtime during an outage?
Many CPAP users do turn off the humidifier specifically to extend battery runtime during travel or an outage, since it roughly doubles power draw for comfort rather than therapy effectiveness — but this is a personal comfort and health decision worth discussing with your medical equipment provider if you're unsure.