Published September 13, 2026 · Reserve Current editorial guide · Updated September 24, 2026
Quick answer: Watts (W) measure power — how fast energy is used right now. Watt-hours (Wh) measure energy — how much is stored or used over time. A 1,000Wh battery with a 100W load gives 10 hours in theory, or about 7.2 hours in our model with 85% efficiency, 10% reserve and 8W idle draw.
Watts describe the demand right now
A watt (W) is a unit of power. Think of a 60W load as the rate at which an appliance is using energy at a particular moment. A station’s continuous AC output rating tells you the combined load its inverter is designed to supply under its specified operating conditions. A large capacity does not automatically mean a powerful inverter.
Watt-hours describe an amount of energy
A watt-hour (Wh) is a unit of energy. A steady 100W load uses 100Wh in one hour, or 400Wh in four hours. One kilowatt-hour is 1,000Wh. The capacity printed on a battery is not necessarily the energy you will receive at an AC outlet: conversion losses, internal consumption and your chosen reserve all reduce it.
A simple example
Imagine a 1,000Wh battery supplying a constant 100W load. Dividing 1,000 by 100 gives ten hours in an ideal calculation. At 85% conversion efficiency with 10% held in reserve and 8W of battery-side idle use, our model gives about 7.2 hours. These are illustrative assumptions, not a tested performance result.
Check power and energy separately
First check whether the station can start and continuously run your selected equipment. Then estimate how long it can do so. The runtime calculator addresses energy. It does not verify starting current, waveform requirements, outlet ratings or installation compatibility.
Frequently asked questions
What is the difference between watts and watt-hours?
A watt is a unit of power: the rate of energy use at a moment. A watt-hour is a unit of energy: a steady 100W load uses 100Wh in one hour. 1kWh equals 1,000Wh.
How long will a 1,000Wh power station run a 100W device?
Ten hours in an ideal calculation. With 85% conversion efficiency, a 10% reserve and 8W of idle draw, our model estimates about 7.2 hours. Real results depend on the product and conditions.
Does a bigger battery mean more power?
No. Capacity (Wh) is energy; the continuous AC output rating (W) is the inverter's power limit. A large battery does not automatically have a powerful inverter.