What Size Power Station Do I Need?
Two numbers decide it: the watts your biggest device pulls at once, and the watt-hours everything adds up to over a day. Here is how to get both.
The short answer
| Appliance | Running watts | Surge watts | Per day |
|---|---|---|---|
| Phone charging | 10W | — | 20-40Wh |
| LED lights | 5-15W | — | 40-90Wh |
| Laptop | 45-65W | — | 150-400Wh |
| CPAP, no humidifier | 30-60W | — | 180-400Wh |
| CPAP with humidifier | 70-120W | — | 500-900Wh |
| 12V camping fridge | 45-60W | 150W | 400-550Wh |
| Full-size refrigerator | 100-200W | 600-1,200W | 1,000-1,500Wh |
| Starlink terminal | 50-75W | — | 1,200-1,800Wh |
| Microwave | 900-1,200W | 1,500W | 50Wh per 3 min |
| Electric kettle | 1,200-1,500W | — | 100Wh per boil |
| Space heater | 1,500W | — | 1,500Wh per hour |
| RV rooftop air conditioner | 1,200-1,800W | 3,000W+ | 10kWh+ per day |
Almost everyone asking this question is really asking two separate questions at once, and mixing them up is what leads to the wrong purchase.
Watts are a rate — what a device pulls at any given instant. They determine whether the power station can run the device *at all*. Watt-hours are a quantity — how much energy the battery holds. They determine *how long*. A 300W unit cannot run a 1,500W kettle for one second, no matter how big its battery. A 2,000W unit with a small battery runs the kettle and then dies. You need both numbers right.
Step 1: find your biggest single load
Go down your list and find the highest running-watts figure. That number sets the minimum continuous AC output you can buy. If it is a kettle, a microwave, a griddle or a hair dryer, you are shopping at 1,500W or above and most of the small units are out immediately.
Then check whether that device has a motor or a compressor. If it does — fridge, freezer, pump, air conditioner, some power tools — find the surge figure too. A compressor that runs at 150W can demand 600-1,200W for a fraction of a second at start-up. A unit rated 300W continuous with a 600W surge will run a small 12V fridge and trip on a full-size one. This is the single most common sizing failure, and it is invisible until the moment it isn't.
Step 2: add up a realistic day
For each device: watts x hours = watt-hours. Add them all. Then add roughly 20% on top, because inverting DC to AC is not free — expect to lose somewhere in the region of 10-15% to conversion, plus a margin so you are not planning to hit zero.
Step 3: sanity-check the weight
This is the step people skip, and it is the one that decides whether the unit ever leaves the garage. Published weights in the 1kWh class run from 23.8 lb to 35.27 lb — roughly a 48% spread for the same amount of stored energy. Above 2kWh you are into 60 lb and beyond, and above 3kWh you are buying something with wheels. If the unit is going to be carried, the weight guide is worth five minutes before you commit.
The capacity tiers, in plain terms
| Capacity | What it honestly covers | Typical weight |
|---|---|---|
| 250-300Wh | Phones, lights, a laptop, a CPAP without humidifier for one night | 8-11 lb |
| 500-800Wh | All of the above plus a 12V fridge for about a day | 12-20 lb |
| 1,000-1,200Wh | A fridge for two nights, or a careful day of home backup | 24-36 lb |
| 2,000Wh | A comfortable full day of home backup, or several days of van loads | 50-60 lb |
| 3,000-4,000Wh+ | Multi-day outage, 240V loads, wheels required | 100 lb and up |
Buy for the trip you take, not the trip you imagine
The most expensive mistake in this category is not under-buying. It is buying 2kWh for a use case that needed 500Wh, discovering it weighs 55 lb, and leaving it at home. Capacity you do not carry is capacity you do not have. If your honest answer is 'mostly weekends, sometimes a fridge', size for that and accept that the one trip a year where you wanted more is cheaper to solve with a panel than with 30 extra pounds.
Once you have a number, the roundups pick up from here: best portable power stations for the overall shortlist, camping and van life for the situational ones, and home backup if the outage is the reason you are here.
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