More runtimeBigger power station
More watt-hours means more hours. Check the inverter and surge ratings cover what you plug in.
Add what you plug in to see the capacity you need.
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Power station runtime calculator
How long will your portable power station run what you plug in? Enter its capacity and your appliances. Results update as you type.
- Checks inverter and surge
- Free, no sign-up
- Runs in your browser
Power station runtime calculator
Your power station
What will you plug in?
How long it runs
Runtime in hours, total load, and checks against the inverter and surge ratings.
How it works
A power station's battery is rated in watt-hours (Wh), the energy it holds. Your appliances draw watts (W). Runtime is the energy divided by the draw, after the losses of turning battery power into wall-socket power.
- 1Usable energybattery Wh × 0.85. The 0.85 covers inverter and battery losses on the AC outlets.
- 2Running loadrunning W × quantity, added up for everything plugged in at once.
- 3Runtimeusable Wh ÷ running load, assuming everything runs the whole time.
The load must also stay under the station's continuous inverter rating, and the moment a motor starts must stay under its surge rating. Enter both and the calculator checks them. Fridges and freezers cycle on and off, so they run longer than the continuous figure.
Worked example: a 1,024 Wh station with a fridge, router and lights
A refrigerator, a router and modem, and four LED bulbs, using the example figures in the calculator:
Running load150 + 20 + 4 × 10 = 210 W
Usable energy1,024 Wh × 0.85 = 870 Wh
Runtime870 Wh ÷ 210 W = about 4 h 9 min
The fridge needs about 1,200 W for a moment as its compressor starts, so the station's surge rating must cover 1,260 W. Because the fridge cycles, the real runtime is longer than 4 hours.
Frequently asked questions
How long will a 1,000 Wh power station run a fridge?
A typical fridge draws about 150 W while its compressor runs. 1,000 Wh × 0.85 ÷ 150 W is about 5.7 hours of continuous running. Because a fridge switches on and off, it usually lasts longer than that in practice. Check that the station’s surge rating covers the fridge starting, often 1,200 W or more.
Why multiply the battery capacity by 0.85?
Converting the battery’s DC power to the AC your appliances use loses energy as heat, and most stations keep a small reserve. 85% is a reasonable planning figure for AC loads. DC and USB outputs lose less.
What is the difference between Wh and W?
Watt-hours (Wh) is how much energy the battery holds, like the size of a fuel tank. Watts (W) is how fast your appliances use it. Runtime is the first divided by the second.
Why does my station run small loads for less time than calculated?
The inverter uses power just by being on, often 10 to 25 W. With a 20 W router that idle draw can double the real consumption. Use the station’s DC or USB outputs for small devices where you can.
More backup power tools
More runtime for your outage
Two ways to run longer. Sizes appear once the calculator has a result.
We may earn a commission from links on this page. How this works
Keep your stationExpansion battery
Many stations take an extra battery that adds capacity without a second inverter.
Add what you plug in to see how much extra capacity helps.
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