Picking a portable power station by price or brand name is the fastest way to end up with the wrong one. What size portable power station do I need is really a math question, not a shopping question, and the math takes about five minutes once you know the formula.
The category has grown fast for a reason. The portable power station market is projected to keep expanding through the early 2030s as more people buy one for camping, remote work, or backup power during outages. More buyers means more confusing size charts and more chances to overspend on capacity you don’t need, or worse, underspend and get stuck with a machine that dies halfway through the night.
This guide skips the marketing tiers and gives you the actual formula, the real wattage numbers for common devices, and the mistakes that trip up first-time buyers.
How Do You Calculate the Right Power Station Size?
Add up the running watts of every device you’ll use, multiply each by the hours you’ll run it, then divide the total by 0.85 to account for inverter and charging losses.
Here’s the formula written out: (Watts × Hours) ÷ 0.85 = Watt-hours needed.
Say you want to run a 60W laptop for 4 hours and a 15W router for 8 hours. That’s 240Wh for the laptop plus 120Wh for the router, or 360Wh total. Divide by 0.85 and you land at about 424Wh. A 500Wh unit gives you comfortable room above that number.
Jackery explains the watt-hour math the same way: watt-hours measure total stored energy, while watts measure the rate that energy is used or delivered. You need both numbers to size a power station correctly, not just one.
Capacity Tiers: Which Wh Range Actually Fits Your Situation
Not every buyer needs the same size, so here’s how the main capacity ranges map to real use cases.
Under 500Wh. Good for charging phones, running LED lights, and topping off a laptop or two. Not enough for anything with a compressor or heating element.
500 to 1,000Wh. The sweet spot for weekend camping trips, CPAP use over multiple nights, and short power blips. If this fits your plans, our portable power stations for camping picks cover this range well.
1,000 to 2,000Wh. Where you start running a mini fridge for a full day or covering a handful of essentials during a longer outage. Our budget picks under $1,000 mostly live in this tier.
2,000Wh and up. Built for home backup: a full-size fridge, a sump pump, a modem and router, and a few lights running for a day or more. See our best portable power stations for home backup for models sized to handle this.
How Much Power Do Everyday Devices Actually Use?
Most people overestimate how much power their gadgets pull. Here’s what the common ones actually draw while running:
| Device | Typical running watts |
|---|---|
| Phone charging | 10 to 20W |
| Wi-Fi router | 10 to 20W |
| Laptop | 45 to 65W |
| LED lights | 10 to 50W |
| Box fan | 50 to 100W |
| Mini fridge | 60 to 100W average |
| Full-size fridge | 100 to 200W average, cycling |
| CPAP without humidifier | 30 to 60W |
| Coffee maker | 800 to 1,200W |
| Window AC unit | 500 to 1,200W |
These numbers come from Jackery’s appliance wattage chart and match the ranges EcoFlow lists for common household devices. Notice the gap between something like a phone charger and a coffee maker. That gap is exactly why sizing by “what I plan to plug in” beats sizing by price point.
Want the full device-by-device breakdown, including runtime estimates? Our guide to what a portable power station can run goes deeper on individual appliances.
What Size Do You Need to Run a CPAP All Night?
Most CPAP machines without a heated humidifier draw between 30 and 60 watts, so a 300 to 500Wh power station covers one full night with a comfortable buffer.
Running the math: a 40W CPAP for 8 hours uses 320Wh. Divide by 0.85 for inverter loss and you’re at roughly 376Wh for one night. ResMed’s own power consumption documentation shows this climbs when a heated humidifier or heated tubing is added, sometimes pushing draw closer to 90 to 100 watts.
If you want more than one night without recharging, or you use a humidifier, size up to 500 to 700Wh. Traveling and camping with a CPAP is one of the most common reasons people buy a power station in the first place, which is part of why the 500 to 1,000Wh tier sells so well.
What Size Do You Need to Keep a Refrigerator Running?
A standard fridge only draws its full wattage about a third of the time, since the compressor cycles on and off to hold temperature, so a 1,000 to 2,000Wh power station can run a mini or standard fridge for a full day or more.
The compressor might be rated at 700W, but it isn’t running constantly. The U.S. Department of Energy explains that refrigerators cycle on for roughly one-third of the time they’re plugged in, which means the real-world average draw is far lower than the nameplate number.
That’s why a 2,000Wh station can often keep a fridge running for 16 to 18 hours even though the math on paper looks tighter. If your fridge is the main appliance you’re planning around, lean toward the higher end of your calculated number, not the lower end.
Capacity vs. Output: Why Watt-Hours Alone Can Mislead You
Watt-hours tell you how long a power station can run something. Watts, specifically the continuous output rating, tell you what it can start and keep running at all.
These are two different specs, and mixing them up is where a lot of buyers get burned. A power station can have plenty of stored energy (Wh) but not enough output power (W) to start a device with a motor or compressor.
That’s because appliances like fridges, fans, and power tools need a short burst of extra power to start up. EcoFlow notes that this startup surge can hit two to three times the appliance’s running wattage for a second or two before settling down. Anker SOLIX flags the same issue with devices like space heaters and refrigerators: if the power station’s surge rating can’t cover that spike, it shuts off instead of starting the appliance.
So before you buy based on Wh alone, check the continuous and surge wattage ratings too, especially if a compressor or motor is on your list.
Common Sizing Mistakes to Avoid
Buying the exact number your formula spits out. Real-world use is messier than a spreadsheet: devices run longer than planned, weather changes your fan or heater needs, and batteries lose a little capacity over time. Build in a buffer of at least 20 percent above your calculated Wh.
Ignoring surge watts. A power station with plenty of Wh capacity can still fail to start a fridge or power tool if its surge output is too low. Check both numbers before buying, not just the headline capacity.
Forgetting the efficiency loss. Power doesn’t move through an inverter for free. Jackery’s own sizing calculator builds in the same efficiency loss, noting that even lithium batteries only run at 90 to 98 percent efficiency. That 0.85 divisor in the formula isn’t optional, it’s the difference between a power station that lasts as long as you planned and one that runs out early.
Comparing a power station to a gas generator without weighing noise, fumes, and maintenance. If you’re still deciding between the two, our portable power station vs. generator comparison breaks down where each one actually wins.
Bottom Line
Sizing a portable power station comes down to one formula: add up your devices’ watts times hours, divide by 0.85, then round up. From there, the tiers do the rest of the work. Light phone and laptop use fits under 500Wh, weekend camping and CPAP use fits 500 to 1,000Wh, and anything with a fridge or longer outage coverage in mind belongs in the 1,000 to 2,000Wh range or higher.
Buy a size bigger than your exact math whenever you can. Batteries lose a little capacity over years of use, and you’ll almost always end up plugging in one more device than you planned for.
Once you know your target Wh range, browse our full lineup of top portable power station picks to find a model that matches it.
Frequently Asked Questions
Is a 300Wh power station enough for camping? A 300Wh power station covers light use like phone charging, a headlamp, and a small fan for a night or two, but it won’t run a cooler with a compressor or a CPAP with a humidifier for long. For most weekend camping trips, 500 to 1,000Wh gives you more comfortable margin.
How many watt-hours do I need for a weekend power outage? For basics like a router, a few lights, and phone charging over a weekend, 500 to 1,000Wh usually gets you through. If you want to keep a fridge running too, size up to 1,000 to 2,000Wh so the compressor cycling doesn’t drain the battery early.
What size portable power station runs a mini fridge? A mini fridge typically averages 60 to 100 watts of running power because of compressor cycling, so a 500 to 1,000Wh power station can usually keep one running for most of a day. For a full day or more, 1,000 to 2,000Wh gives you a safer buffer.
Can a portable power station run a CPAP all night? Yes. Most CPAP machines without a heated humidifier draw 30 to 60 watts, so a 300 to 500Wh power station covers one full night. If you use a heated humidifier or want multiple nights per charge, look at 500 to 700Wh or more.
Should I buy a bigger power station than my calculated number? Yes, add at least a 20 percent buffer above whatever your formula gives you. Real-world use rarely matches a spreadsheet exactly, and battery capacity naturally drops a little as the unit ages.
