Free Tool
Power Station Runtime Calculator
Add your devices and find out how long a power station will keep them running, or work backwards from the hours you need to the capacity you should buy.
Runtime is roughly the power station’s usable capacity in watt-hours divided by your device load in watts, minus about 15 percent for inverter losses. A 1,000Wh station running a 100W load lasts around 8 to 9 hours. Enter your devices to get a real figure.
Interactive Tool
Power Station Runtime Calculator
Estimates account for usable battery capacity, inverter losses and temperature. Real-world runtime varies with device load patterns and battery age.
Want to understand the maths behind these numbers? Read our full guide on how to calculate how long a power station will last, covering usable capacity, inverter efficiency and cold-weather performance.
Frequently asked questions
How long will a power station last?
Divide the usable capacity (Wh) by the total load (W), then knock off about 15 percent for inverter inefficiency. A 500Wh station running a 60W TV lasts roughly 7 hours. The calculator handles multiple devices at once.
How do I work out a device’s watt-hours?
Multiply its power draw in watts by the hours you run it. A 90W fridge running effectively 8 hours a day uses about 720Wh. Check the label or plug it into a power meter for an accurate figure.
Why is real runtime less than the rated capacity?
No inverter is 100 percent efficient, and some capacity is held back to protect the battery. Expect about 85 percent of the rated watt-hours to reach your devices, a little less for high loads.
What size power station should I buy?
Add up the watt-hours of everything you need to run for as long as you need it, then add 15 to 20 percent headroom. Match the continuous watt rating to your highest-draw device, and check the surge rating for anything with a motor.
