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How Many Watts Do I Need?
Tick what you want to run at the same time. We’ll tell you the continuous and surge wattage your power station has to deliver.
The short answer
Add up the running watts of everything you’ll have plugged in at once. That’s your continuous output. Then add the biggest startup surge among them — anything with a motor or compressor briefly draws two to three times its running watts. Most homes covering a fridge, lights, internet and phones draw only about 250W continuous — but need 900W of surge headroom for the fridge compressor, which is why a 600W–1,000W unit is the usual answer rather than a 300W one.
Wattage calculator
Tick everything you’d run at the same time. Nothing is sent anywhere.
Work it out by hand
The calculator needs JavaScript, which isn’t running. The maths takes a minute on paper:
Step 2 find the item with the biggest startup surge
Step 3 continuous + (that surge − its own running watts) = surge watts
Typical US figures. Your appliance label always wins — it’s on the back or underside.
Tick something to start
Your recommendation appears here.
Watts and watt-hours aren’t the same thing
Watts decide what a power station can run. Watt-hours decide how long it runs for. A unit with a huge battery and a small inverter still won’t start a microwave, and a unit with a big inverter and a small battery will run it for four minutes.
This page answers the first question. For the second — battery capacity and runtime — use the full sizing guide, which has a calculator for watt-hours.
Why surge watts matter more than you’d expect
Anything with a motor or compressor — fridges, freezers, pumps, air conditioners, power tools — pulls a burst of power for a fraction of a second when it starts. A fridge that runs happily at 150W can spike past 800W at the moment the compressor kicks in.
This is the single most common reason a power station “stops working”. It ran the fridge for an hour, then shut off. Nothing was broken — the compressor restarted, the surge exceeded the inverter’s limit, and the unit protected itself.
Rule of thumb: for motor-driven appliances, budget two to three times the running watts. Resistive loads — kettles, heaters, toasters, lights — have no surge at all, so what you see is what you get.
Common appliance wattages
| Appliance | Running watts | Startup surge |
|---|---|---|
| Refrigerator (full size) | 150 W | 800 W |
| Chest freezer | 100 W | 600 W |
| Wi-Fi router + modem | 20 W | — |
| LED lights (5 bulbs) | 50 W | — |
| Phone charging | 10 W | — |
| Laptop | 60 W | — |
| TV (55″ LED) | 120 W | — |
| CPAP machine | 40–90 W | — |
| Box fan | 50 W | 150 W |
| Coffee maker | 1,000 W | — |
| Microwave (1,000W output) | 1,200 W | 1,500 W |
| Electric kettle | 1,500 W | — |
| Space heater | 1,500 W | — |
| Window AC (8,000 BTU) | 700 W | 1,800 W |
| Furnace blower | 600 W | 1,500 W |
| Sump pump (1/3 HP) | 800 W | 2,000 W |
| Well pump (1/2 HP) | 1,000 W | 2,100 W |
| Circular saw | 1,400 W | 2,300 W |
| Starlink dish | 60 W | — |
Typical figures for US 120V appliances. Older units and larger models draw more — check the label if you’re close to a limit.
Quick questions
How do I find my appliance’s wattage?
There’s a label on the back or underside listing watts. If it shows amps instead, multiply by 120 for US outlets — 5 amps is 600 watts. Startup surge is almost never printed, so use two to three times the running figure for anything with a motor.
What happens if I exceed the wattage?
The unit shuts off to protect itself. It isn’t damaged and usually restarts with a button press once you unplug something. Repeatedly pushing it to the limit does shorten inverter life, though, so size with headroom rather than exactly.
Can I just run things one at a time?
Yes, and it’s a legitimate way to buy a smaller unit. Size for your largest single appliance plus anything that must stay on permanently — a fridge, for instance — then stagger the rest. Just remember the fridge restarts on its own schedule, not yours.
Do USB ports count toward the wattage?
They draw from the same battery but bypass the AC inverter, so they don’t count against the continuous AC rating. Charging a laptop over USB-C instead of its wall adapter also saves roughly 15% of the energy, which is worth doing during an outage.
Know Your Watts. Now Check the Runtime.
Wattage tells you what it can run. Capacity tells you how long. The full guide covers both, or send us your list and we’ll size it.