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Sizing a portable power station comes down to two numbers on the spec sheet. Watts (W) tell you what it can run at the same time. Watt-hours (Wh) tell you how long it can run it. Most buyers look at only one of them and end up with a station that either trips on startup or dies halfway through the night. Here is how to size both, with examples of what each class actually runs.
A station with big output but a small battery runs a microwave for a few minutes. A station with a big battery but small output runs a fridge for days but cannot start a space heater.
Step 1: List each device and its running watts (on the label or charger).
Step 2: Add up the watts of everything that runs at the same time. Choose a station whose continuous output beats that number, with extra headroom for anything with a motor.
Step 3: For each device, multiply watts by the hours you will run it. Add those up to get your daily watt-hours.
Step 4: Divide by 0.85 to cover inverter losses. That is the minimum battery capacity you need.
Example: a CPAP at 50W for 8 hours (400Wh) plus a laptop at 60W for 4 hours (240Wh) comes to 640Wh. Divided by 0.85, that is about 750Wh, so a 1,000Wh station covers it with margin.
A 1,000W to 1,500W station with about 1,000Wh of battery handles the essentials: a refrigerator overnight, a CPAP for several nights, Wi-Fi, lights, phones, laptops, and a TV. It can briefly run a small microwave or coffee maker, but those drain the battery fast.
At 2,000W to 2,200W output with about 2,000Wh, you can run a fridge for more than a day plus Wi-Fi, lights, and a TV, or a full-size microwave, coffee maker, and most power tools one at a time. This is the sweet spot for camping trips and for riding out a typical outage.
A 3,000W-plus station with about 3,000Wh covers a fridge, freezer, Wi-Fi, lights, and fans for around two days, and it can run a 1,500W space heater for under two hours or a small window AC for a couple of hours. Many units in this class connect to a manual transfer switch to back up selected home circuits.
Running a refrigerator is the most common reason people buy one. See how long a portable power station runs a refrigerator for the detailed runtimes.
Prices are current at Krato Power. Browse them all in Portable Power Stations.
Outgrowing a portable unit? See our 48V Server Rack Batteries for a permanent home battery system.
It depends on the load. With about 3,000Wh of battery, it runs a 100W load for roughly 25 hours, a refrigerator for about two days, or a 1,500W space heater for under two hours.
Plan to load a power station to no more than about 80 percent of its continuous output. That leaves headroom for startup surges and keeps the inverter from running at its limit.
Most modern LiFePO4 stations are built to stay plugged in, and many work as a UPS that switches over automatically when the grid drops. Check the manual for your model's pass-through and storage guidance.
If you lose power a few times a year, camp, or need a CPAP or fridge covered, yes. It runs quietly, makes no fumes, and works indoors, which a gas generator cannot.
Send the Krato Power team your device list and how long you need power, and we will size a station for you. Call 888-855-7286 or browse Portable Power Stations.
This is general information, not electrical or professional advice. Connecting to home circuits requires a transfer switch installed by a licensed electrician per local code.