What size power station do I need? Add up the watts of everything you want to run at the same time, then multiply that by the hours you want power to last to get watt-hours. Pick a unit whose output covers the watts and whose capacity covers the watt-hours, with some room to spare.
There is no magic number, because the right size depends on what you plug in and for how long. This guide gives you a three-step method, a worked example with simple numbers, and a plain look at who should skip a power station.
Watts vs. watt-hours in plain words
Two numbers on a spec sheet cause most of the confusion. Watts measure power, which is how much a device pulls at one moment. Watt-hours (Wh) measure energy, which is how much is stored or used over time.
Pecron, a power station maker, uses a water picture. Watts are like the size of the pipe, and watt-hours are like the size of the tank. A wide pipe lets a lot flow at once, and a big tank lasts longer. You need both to be big enough for your plan.
The link between the two is simple. The U.S. Department of Energy gives the formula for energy use as watts times hours, divided by 1,000, which gives kilowatt-hours. Skip the division and you get watt-hours: watts times hours.
Step 1: list what you want to run
Write down every device you want to power, then find its wattage. The Department of Energy says the label is usually on the bottom, back or nameplate of the device. It also says the number on the label is the most power the device draws, not what it uses all the time.
If the label shows amps instead of watts, multiply amps by volts. A label that says 1.5 amps at 120 volts works out to 180 watts, and rounding up to 200 gives you a small cushion. The Department of Energy says most U.S. appliances run on 120 volts. Its own examples show how it works: an electric kettle labeled 1,500 watts, and a paper shredder at 360 watts, which is 120 volts times 3 amps.
You can also use a watt meter. Plug the meter into the outlet, plug the device into the meter, and read the watts. The Department of Energy notes these monitors work only for 120 volt devices.
Anker SOLIX, another maker, suggests splitting the list into must-run items and nice-to-have items. That helps later, when you decide what to cut if the numbers come out too big.
Step 2: add up watts and hours
Now you need two totals.
- Total watts at once. Add the watts of everything that will run at the same time. This is the output your power station must cover.
- Total watt-hours. For each device, multiply its watts by the hours you want it running. Add those up. This is the capacity you need.
Here is an example with made-up numbers. Say a 60 watt device and a 40 watt device run together for 5 hours. The output needed is 60 plus 40, or 100 watts. The energy needed is 100 watts times 5 hours, or 500 watt-hours.
Real units lose some energy when they turn battery power into the kind of power your devices use, so leave a buffer. Anker SOLIX’s guide multiplies by 1.2, a 20% buffer, which turns the example above into about 600 watt-hours. Pecron takes a different route and assumes about 85% of advertised capacity is usable, so it divides by 0.85. Both are the makers’ own planning figures, not test results, but both say the same thing: do not size to the exact number.
Why startup watts matter
Some devices need a short burst of extra power to start. Pecron lists refrigerators, pumps, compressors and motor-driven tools. Its example is an appliance labeled 800 watts that may briefly need more than that. Pecron adds that there is no universal startup multiplier, so the maker’s specs are the place to look.
That is why power stations list a surge or peak output next to the regular output. Anker SOLIX says the surge number must cover the biggest startup spike, and that a unit with too little surge output may fail to start motor-driven appliances. Check both numbers on any unit you are considering.
Refrigerators are a special case because they cycle on and off. The Department of Energy suggests dividing the time a refrigerator is plugged in by three to estimate the hours it runs at full power. That helps with the watt-hour math, but it does not remove the startup question.
What size power station do I need by use?
Do the math twice: once for what you must run, and once for everything you might run. If the first number fits a smaller unit, you have a clear choice to weigh.
The table lists what to add up for common uses. It has no wattage numbers on purpose, because the label on your own device is the only figure that fits your own gear.
| Use | What to list | Watch for |
|---|---|---|
| Camping | Phones, lights, a laptop, a small fan | Hours between recharges |
| Remote work | Laptop, monitor, router, desk lamp | Total watts at once |
| Short outage | Phones, router, lights, a fridge if needed | The fridge’s startup surge |
| RV or van trips | Fridge, fan, lights, chargers | How you will recharge on the road |
If solar will be your main way to recharge, Anker SOLIX says to size capacity more generously, because solar input depends on the weather.
What can a 1000w power station run?
A 1,000 watt rating describes output, not capacity. A 1000w power station can run devices that add up to 1,000 watts or less at the same moment, as long as their startup surges fit within the unit’s surge rating. How long it lasts depends on its watt-hours.
The Department of Energy’s electric kettle example, at 1,500 watts, is over that line, so a 1,000 watt unit could not run it no matter how big the battery is. The paper shredder example, at 360 watts, is under the line, though a motor can need extra power to start. For your own devices, add up the labels and compare.
Comparing units
Once you have your numbers, compare them with the output, capacity and surge figures on each product page. ALLPOWERS sells portable power stations, home backup energy systems and foldable solar panels, according to our ALLPOWERS page. Read each listing’s own specs and match them to your list, instead of picking by size alone.
Who should skip a power station
A power station is not the right tool for every job.
- Whole-home backup. Powering a house is a job for a licensed electrician and a system built for it. Do not connect a power station to your home wiring yourself.
- Heavy appliances. If a device’s label shows more watts than the unit’s output, it will not run. The kettle example above is one case.
- Medical equipment. Check the device’s wattage on its label, then ask your doctor or equipment supplier about backup power. Do not guess.
- Tiny needs. If your math gives a small number, a large unit may be more than you need.
Safety basics
Follow the maker’s manual for where to place the unit, how to ventilate it and how to charge it. Add up running watts before you plug things in, and stay under the rated output. Keep cords in good shape, and do not overload a single outlet on the unit. If the manual and this guide disagree, the manual wins.
FAQ
Which size works for camping?
Camping loads are often small, so the hours between recharges can matter more than the watts. List your devices, add up the watt-hours for the trip, and add a buffer. A solar panel changes the math, so plan for cloudy days.
Can a power station run a refrigerator?
It can if the unit covers the fridge’s label watts, its startup surge and the watt-hours you need. The Department of Energy notes that fridges cycle on and off, while Pecron and Anker SOLIX both say to check surge ratings for motor-driven appliances.
How long will it run my devices?
Divide the unit’s watt-hours by your total watts, then allow for losses. By Anker SOLIX’s rule, 600 watt-hours covers a 100 watt load for 5 hours, because 100 times 5 times 1.2 equals 600. Real results vary by unit and use.
Do I need more capacity with solar panels?
Plan on more. Anker SOLIX says to size capacity more generously when solar is the main way you recharge, because panels depend on the weather. Check each panel’s own listing for what it can feed to the unit.
The short version
List your devices, add up the watts and the hours, and leave a buffer. Check surge output for anything with a motor. If the numbers are big, or a medical device is involved, ask an electrician, a doctor or the equipment supplier before you buy.
