Guide
If you only learn one thing before buying a portable power station, make it this: watts and watt-hours are not the same, and mixing them up is the number-one reason people end up with the wrong unit. The good news is the difference is genuinely simple once you have the right analogy.
A watt (W) is a rate — how much energy something uses or delivers at any given instant. On the appliance side, it's how hard a device pulls: a laptop draws about 60W, a space heater 1,500W. On the power station side, watts describe the inverter's output — the maximum load it can supply at once. If your combined load exceeds the station's rated output watts, it can't run everything, no matter how big the battery is.
A watt-hour (Wh) is an amount — power multiplied by time. It's the size of the battery, or how much total work the station can do before it's empty. One watt-hour is one watt sustained for one hour. A 1,000Wh station can, in theory, deliver 1,000W for one hour, 100W for ten hours, or 10W for a hundred hours.
Think of a water tank. Watts are like the width of the pipe — how fast water can flow out at once. Watt-hours are like the total volume in the tank — how much water there is. You need a pipe wide enough to run your appliance (enough watts to turn it on) and a tank big enough to keep it running as long as you need (enough watt-hours). A wide pipe on a tiny tank empties fast; a huge tank behind a narrow pipe can't push enough at once. The goal is a sensible match between the two for the job you have in mind.
| Watts (W) | Watt-hours (Wh) | |
|---|---|---|
| Measures | Power / rate | Energy / capacity |
| On appliances | How much it draws now | — |
| On a station | Max output at once | Battery size |
| Determines | What you can run | How long you can run it |
The relationship is: watt-hours ÷ watts ≈ hours of runtime (minus inverter losses). The Department of Energy uses the same idea to estimate appliance running costs: its Estimating Appliance Energy Use guide multiplies an appliance's wattage by hours of use and divides by 1,000 to get kilowatt-hours — one kilowatt-hour is simply 1,000 watt-hours.
Numbers make this concrete. Take two popular 1,000Wh-class stations. The Jackery Explorer 1000 holds 1,002Wh and delivers 1,000W of continuous AC output (2,000W surge). The EcoFlow DELTA 2 holds a nearly identical 1,024Wh but pushes 1,800W continuous (2,700W surge). Their tanks are the same size; their pipes are very different.
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Now try to run a 1,500W space heater. On the Jackery, the heater's draw exceeds the 1,000W output, so it simply won't run — the full 1,002Wh battery is irrelevant because the pipe is too narrow. On the DELTA 2, the same heater runs fine (1,500W is under 1,800W), and runtime is roughly 1,024Wh ÷ 1,500W ≈ 0.68 hours, or about 35–40 minutes once you subtract inverter losses. Same energy, completely different outcome — decided entirely by the watts, not the watt-hours.
Once a device is within a station's output, watt-hours set the clock. Here's roughly how long a 1,000Wh station (about 90% usable after losses) lasts at different draws:
| Device (running watts) | Approx. runtime on ~1,000Wh |
|---|---|
| Phone charger (10W) | ~90 hrs |
| Laptop (60W) | ~15 hrs |
| 32" TV (90W) | ~10 hrs |
| Mini fridge (avg ~40W) | ~22 hrs |
| Microwave (1,000W) | ~0.9 hr |
When you scan a product listing, three numbers tell you almost everything. The capacity in Wh answers "how long?" The continuous AC output in W answers "what can I run at once?" The surge or peak W answers "will it survive a motor starting up?" A station listed as "1,024Wh · 1,800W · 2,700W surge" is telling you, in order: a mid-size battery, enough output for most household devices, and headroom to start a fridge or power tool. If a listing only shouts one big number, find the other two before you judge it — a headline "2,200W" output means nothing without knowing the watt-hours behind it.
Is a higher-Wh station always better? No. More watt-hours only extend runtime. If the output watts are too low, extra capacity can't help you run a high-draw appliance at all.
Why won't my 1,000W station run a "1,000W" appliance? Rated appliance watts are often nominal, and many devices spike above their label at startup. Leave roughly 10–20% headroom between your load and the station's continuous output.
Do watt-hours change with the appliance? No — watt-hours are a fixed property of the battery. How fast you spend them depends on the watts your devices draw.
How do watts and watt-hours relate to my electric bill? Your utility bills in kilowatt-hours — the same unit, scaled up. A 60W laptop left on for 10 hours uses 600Wh, or 0.6 kWh. Thinking in these units is the fastest way to predict both your runtime on a power station and your monthly usage at home.
Both numbers appear on every spec sheet, and both matter. Our power station calculator handles them together — telling you the watt-hours and output watts your setup needs, or how long a given station will run your gear.