What Size Power Station Do I Need?
Buying a power station before knowing your real power needs is a common (and expensive) mistake. Tell this calculator which devices you want to run and for how many hours, and it will recommend a capacity — then show you where that lands against common battery sizes.
Select your devices
Total load: 0 WKitchen & Food
Climate & Comfort
Entertainment & Gaming
Electronics & Office
Medical
Lighting
Laundry
Add a custom device
Select at least one device to calculate the capacity you need.
- 500 Wh
- 1,000 Wh
- 1,500 Wh
- 2,000 Wh
- 3,000 Wh
This is an estimate. Real-world runtime can be lower than the theoretical figure due to inverter efficiency losses, fluctuating (not constant) device draw, ambient temperature, battery age/health, and other factors. Always check your power station’s official specifications before relying on it for critical use.
How the sizing calculation works
The calculator inverts the standard runtime formula to solve for capacity instead of time:
Required Capacity (Wh) = (Total Power (W) × Hours) ÷ Efficiency
It then rounds that figure up to the nearest 50 Wh — batteries aren't sold in exact fractional sizes, so a clean, slightly generous number is more useful than a precise one.
Worked example
Say you want to run a mini fridge (70 W) and a few LED lights (20 W) for 10 hours during a power outage, at 85% efficiency. Total load: 90 W. Required energy: 90 × 10 ÷ 0.85 = 1,058.8 Wh, rounded up to 1,100 Wh.
Looking at common reference sizes, a 1,500 Wh power station would comfortably cover this with headroom for a few extra hours or an unplanned extra device.
How much buffer should I add?
The recommended capacity above is a mathematical minimum, not a comfortable target. In practice:
- Add roughly 15–25% on top of the calculated figure to cover efficiency loss under partial load, battery aging, and colder temperatures.
- If you're sizing for an unpredictable event (a blackout of unknown length), round up to the next common capacity tier rather than the exact number.
- If any device on your list is safety-critical (medical equipment, a sump pump, a freezer full of food), size generously rather than to the minimum.
Typical sizing by use case
As a general starting point (always confirm with the calculator using your own devices):
- Phones, lights, small electronics only: 300–500 Wh is often enough for a weekend.
- Camping with a fan, lights, device charging: 500–1000 Wh typically covers 2–4 days.
- Short home blackout (fridge, router, some lights): 1000–2000 Wh usually covers 8–24 hours.
- RV/van life or multi-day home backup: 2000–3000 Wh+ gives meaningful headroom, especially paired with solar recharging.
Frequently asked questions
Is it better to size up or size down when unsure?
Size up. Running out of power mid-task is far more disruptive than carrying slightly more capacity than strictly necessary — and unlike fuel, unused stored energy isn't "wasted," it's just headroom for next time.
Does a bigger power station charge slower?
Generally yes, all else equal — a larger battery takes longer to refill from the same wall outlet or solar panel, since charging speed is limited by the charger/panel wattage, not the battery size. Check your specific unit's charging specifications when comparing options.
Should I size around my most-used devices or my worst-case scenario?
Size around your worst realistic case — the day you actually need backup power is rarely your lightest usage day. Add every device you might reasonably run at once, not just your typical daily set.
What if my required capacity falls between two common sizes?
Round up to the next size, factoring in the buffer recommendations above. A capacity that exactly meets your calculated minimum leaves no margin for efficiency loss, colder weather, or an extra device you forgot to include.