Power Station Size Calculator
Pick what you want to run and for how long. We'll tell you the minimum battery size — and match it to real power stations.
Portable power stations are sold on two numbers — battery capacity (Wh) and output (W) — and most shoppers underbuy one of them. A 1000Wh station with a 500W inverter sounds powerful until you try to plug in a microwave or coffee maker and discover it can't deliver enough wattage. Conversely, a 2000W inverter on a 600Wh battery runs your hairdryer for 18 minutes and then dies. You need both right.
This calculator handles the math two ways. Tell it what you want to run and for how long, and it returns the minimum battery capacity (Wh) and peak output (W) you need. Or pick a use case (emergency backup, van life, camping, CPAP overnight) and it gives you a typical starting point. We pad the result by 15-20% for inverter inefficiency and battery aging — the manufacturer-printed Wh is what a fresh battery delivers under ideal lab conditions, not what you get on year 3.
Three secondary specs that matter once the basic math is right: battery chemistry (LiFePO4 for 3-4× more cycles than Li-ion at slightly higher cost), solar input (the recharge speed that determines whether a station is useful off-grid), and expandable battery options (whether you can grow capacity without replacing the unit). We surface these on the matched stations so you can compare apples-to-apples.
Add a device
Your load
Phone charge
12W × 2h = 24Wh
Laptop
60W × 4h = 240Wh
Recommended power station
Minimum capacity
350Wh
Total load 264Wh + 15% buffer for inverter efficiency & battery reserve.
Peak output needed
60W
Highest single-device wattage. The station's AC output must exceed this number.
How this works
How do I calculate my watt-hour needs?
Add up (wattage × hours) for every device. Then add 15-20% for inverter inefficiency and battery reserve. A 100W laptop for 4 hours = 400Wh × 1.15 = 460Wh minimum. The calculator above does this automatically once you select your devices and runtime — saves you from looking up appliance wattages.
What's the difference between battery capacity (Wh) and output (W)?
Watt-hours measures how much energy is stored (capacity). Watts measure how much power can be delivered at once (output). You need both: enough Wh for your runtime, enough W to power your biggest device. A 2000Wh station with a 500W inverter can't run a microwave even though it has plenty of stored energy.
Should I size up for emergencies?
Yes. Real outages last longer than expected, and solar recharge slows in cloudy weather. For emergency backup, double your daily calculated Wh. The "X-hour fridge runtime" math on manufacturer pages assumes ideal conditions — derate by 30% for cold-weather degradation and aging batteries.
Can a power station run a fridge or coffee maker?
Fridges yes, easily — they cycle on/off and average ~50-100W. Coffee makers and microwaves draw 1000-1500W in short bursts, which exceeds smaller stations' output. Check the AC output spec against your peak device wattage. Look for "surge" or "peak" output, which is briefly higher than continuous — relevant for motor starts on fridges and AC units.
LiFePO4 vs Li-ion — which battery chemistry should I pick?
LiFePO4 (lithium iron phosphate) is the right pick for most home use. Pros: 3000-4500 charge cycles (vs 500-1000 for Li-ion), much safer thermal profile, holds capacity longer in storage. Cons: slightly heavier per Wh, costs 20-30% more. For occasional camping use, Li-ion is fine; for emergency backup or daily use, LiFePO4 pays back.
How important is fast charging?
For RV / van life: very. The difference between 1-hour and 5-hour AC recharge changes how you plan a day. For home emergency backup: less important — you charge from grid before storms, then it sits charged. For solar, look at MPPT input watts: 400W+ input means useful daytime recharge; 100W input is too slow.
Can I expand capacity later?
Some stations support add-on battery packs (Bluetti, EcoFlow, Anker SOLIX). Useful if you want to start small and scale. Caveats: expansion batteries are usually $400-800 and add weight; not all model years are compatible with newer expansion batteries. Check before committing to a brand ecosystem.
Solar panel pairing — what wattage do I need?
Solar input rate matters more than panel wattage. A 1000Wh station with 400W solar input fully recharges in ~3 hours of good sun. With 100W input, it's 12 hours. Match panel watts to the station's max solar input (usually printed on the spec sheet as "Max Solar Input"). Most stations top out at 400-1000W of solar.