Free backup power planning tool
Portable Power Station Size Calculator
Estimate what battery capacity you may need for outages, camping, RV trips, CPAP backup, refrigerator backup, or work-from-home power before you buy.
1. Add devices
Enter the watts and hours for your essential loads: router, laptop, CPAP, lights, refrigerator, or fan.
2. Add losses
Choose AC or DC efficiency and add a reserve margin so your plan is not too optimistic.
3. Get a size
The result gives a planning Wh target and a simple size category for shopping or comparison.
How to Choose the Right Power Station Size
The easiest way to size a portable power station is to estimate how many watt-hours your devices will use. Multiply each device’s typical watts by the number of hours you need it to run, then add everything together. After that, account for efficiency losses and a reserve margin.
Recommended battery size = total device watt-hours ÷ efficiency × reserve margin
Quick Size Examples
200–500Wh
Light backup: phones, LED lights, radios, and small USB devices.
500–1,000Wh
Everyday essentials: laptop, router, monitor, lights, fan, or limited CPAP planning.
1,000–2,000Wh+
Longer backup: refrigerators, freezers, CPAP overnight, RV loads, and outage essentials.
Capacity Is Not the Only Specification
A larger battery stores more energy, but you also need enough output power. Check continuous AC output for regular loads and surge output for refrigerators, freezers, pumps, and other motor loads. Also check solar input limits if you plan to recharge from panels.
| Specification | Why it matters |
|---|---|
| Battery capacity, Wh | Determines how much energy the station can store. |
| Continuous output, W | Determines what devices can run at the same time. |
| Surge output, W | Important for compressors, pumps, and motor loads. |
| Solar input, W | Controls how quickly panels can recharge the battery. |
Related Calculators
Use these tools next to refine your estimate for a specific device or charging setup.
FAQ
What size portable power station do I need?
Add up the watt-hours needed by your essential devices, then account for efficiency losses and reserve margin. Small loads may only need a few hundred watt-hours, while refrigerator or home essentials backup may need 1,000Wh to 2,000Wh or more.
Is a 500Wh power station enough?
A 500Wh power station can be enough for phones, lights, routers, laptops, and some CPAP planning. It is usually limited for refrigerators, heaters, large appliances, or long outages.
Is a 1,000Wh power station enough for home backup?
A 1,000Wh power station can support selected essentials for a limited time, but it may not be enough for whole-home backup. For refrigerators, CPAP machines, routers, and lights together, calculate the combined watt-hours and add a reserve margin.
PowerStationCalc.com provides planning calculators and educational content. Calculations are based on typical device wattage and published specifications. Actual results may vary.
Choose by real use case
Pick a power station size based on what you actually need to run
These planning ranges are simple starting points. Use the calculator above for a more specific watt-hour estimate.
🔦
Emergency basics
Phones, LED lights, radio, and a small router backup. Good for short outages and simple preparedness kits.
Planning range: 200–500Wh
💻
Work-from-home backup
Laptop, Wi‑Fi router, phone charging, monitor, and a few lights. A good match for productivity during brief power cuts.
Planning range: 500–1,000Wh
🧊
Food and essentials
Refrigerator, freezer, CPAP planning, router, lights, and phones. Check surge output before relying on it for compressor loads.
Planning range: 1,000–2,000Wh+
Before you buy, check these 5 things
Battery capacity is only one part of the decision. A power station also needs enough output power, ports, charging speed, and reserve capacity for your use case.
- Capacity: enough watt-hours for your runtime goal.
- Continuous output: enough watts for everything running at once.
- Surge output: important for fridges, freezers, pumps, and tools.
- Charging input: enough solar or wall charging speed for your plan.
- Port mix: AC outlets, USB‑C, DC car port, and any special connectors you need.
Common sizing mistakes
Avoid these mistakes when comparing portable power stations.
Ignoring inverter losses
AC output usually uses more energy than DC or USB. Add an efficiency adjustment so the estimate is not too optimistic.
Forgetting startup surge
A refrigerator may average low watts, but its compressor can need a higher startup surge. Check both numbers.
Using peak watts all day
Some devices cycle on and off. Use measured average watts when possible, especially for fridges and freezers.
Need runtime instead of size?
After you estimate the battery size, use the runtime calculator to see how long a specific power station may run your devices.