What is "load factor"

n. (aeronautics) the ratio of an external load to the weight of the aircraft (measured in g)

Load factor may refer to:

• Load factor (aeronautics), the ratio of the lift of an aircraft to its weight
• Load factor (computer science), the ratio of the number of records to the number of addresses within a data structure
• Load factor (electrical), the average power divided by the peak power over a period of time
• Passenger load factor, the ratio of revenue passenger miles to available seat miles of a particular transportation operation (e.g. a flight)
• Factor loadings in statistics, the exposure to specific factors or components in Factor Analysis or Principal Component Analysis

In aeronautics, the load factor is defined as the ratio of the lift of an aircraft to its weight and represents a global measure of the stress ("load") to which the structure of the aircraft is subjected:

$$n = \frac {L}{W}$$
where:

n = Load factor L = Lift W = Weight

Since the load factor is the ratio of two forces, it is dimensionless. However, its units are traditionally referred to as g, because of the relation between load factor and apparent acceleration of gravity felt on board the aircraft. A load factor of one, or 1 g, represents conditions in straight and level flight, where the lift is equal to the weight. Load factors greater or less than one (or even negative) are the result of maneuvers or wind gusts.

In electrical engineering the load factor is defined as the average load divided by the peak load in a specified time period.

$f_{Load} = \frac{\text{Average load}}{ \text{Maximum load in given time period}}$

Typical example of a large commercial electrical bill: kW Demand = 436 kW; kWh Use = 57,200 kWh; Number of days in billing cycle = 30d

Load Factor [%] = {(57,200 kWh / (30 days X 24 hours per day X 436 kW)} X 100% = 18.22%

It can be derived from the load profile of the specific device or system of devices. Its value is always less than one because maximum demand is always higher than average demand, since facilities likely never operate at full capacity for the duration of an entire 24-hour day. A high load factor means power usage is relatively constant. Low load factor shows that occasionally a high demand is set. To service that peak, capacity is sitting idle for long periods, thereby imposing higher costs on the system. Electrical rates are designed so that customers with high load factor are charged less overall per kWh. This process along with others is called load balancing or peak shaving.

The load factor is closely related to and often confused with the demand factor.

$f_{Demand} = \frac{ \text{Maximum load in given time period}}{\text{Maximum possible load}}$

The major difference to note is that the denominator in the demand factor is fixed depending on the system. Because of this, the demand factor cannot be derived from the load profile but needs the addition of the full load of the system in question.