Load Factor Calculator

A load factor calculator converts period energy use and recorded peak demand into a measure of how consistently an electrical load operates over a defined period. The result is used during preliminary load review to compare average demand with the highest demand imposed on a service, feeder, generator, transformer, or major branch-circuit load.

A high load factor indicates that demand stays relatively close to the recorded peak. A low load factor indicates brief or intermittent peaks relative to the energy consumed over the period. The calculator reports both the load factor and the inverse relationship, the peak-to-average ratio.

Load factor is useful when reviewing whether a measured peak appears representative of continuous operating demand, when comparing different billing periods, and when identifying loads that may create capacity or voltage-drop concerns during short peak conditions.

Period Energy and Peak Demand

The calculation uses three values from the same measurement or estimate period:

Input	Unit	Electrical meaning
Period energy	kWh	Total electrical energy used during the measured or estimated period
Period hours	h	Number of elapsed hours represented by the period energy
Peak demand	kW	Highest demand recorded during that same period

Period energy divided by Period hours produces average demand in kW. Peak demand must represent the same period and demand basis as the energy figure. Combining a monthly kWh total with a peak taken from a different month, a different meter, or a different demand interval produces a ratio that does not represent the load profile.

Utility demand values may be based on interval averaging rather than an instantaneous maximum. A 15-minute, 30-minute, or other utility demand interval can produce a different peak than a short-duration field measurement. Use the available demand definition consistently when comparing periods or equipment.

Calculation Method

The calculator first determines average demand:

\(\displaystyle \text{Average demand (kW)} = \frac{\text{Period energy (kWh)}}{\text{Period hours (h)}}\)

It then calculates load factor:

\(\displaystyle \text{Load factor} = \frac{\text{Average demand (kW)}}{\text{Peak demand (kW)}}\)

The percentage output is:

\(\displaystyle \text{Load factor percent} = \text{Load factor} \times 100\)

The calculator also returns peak-to-average ratio:

\(Peak-to-average ratio = \frac{\text{Peak demand (kW)}}{\text{Average demand (kW)}}\)

Peak-to-average ratio is the reciprocal of load factor. A load factor of 0.60x corresponds to a peak-to-average ratio of approximately 1.6667x.

Calculation Example

Enter the following measured-period values:

Input	Value
Period energy	7,200 kWh
Period hours	240 h
Peak demand	50 kW

Average demand is:

\(\displaystyle \frac{7{,}200\ \text{kWh}}{240\ \text{h}} = \text{30 kW}\)

Load factor is:

\(\displaystyle \frac{30\ \text{kW}}{50\ \text{kW}} = \text{0.6x}\)

Load factor percent is:

\(\displaystyle 0.6 \times 100 = \text{60\%}\)

Peak-to-average ratio is:

\(\displaystyle \frac{50\ \text{kW}}{30\ \text{kW}} = \text{1.6667x}\)

The result shows that the period’s average demand was 30 kW while its highest recorded demand was 50 kW. Average demand operated at 60% of peak demand over the 240-hour period.

Electrical Planning Use

Load factor helps organize a preliminary capacity review, but it does not establish conductor ampacity or overcurrent protection requirements.

A measured 50 kW peak may lead to further review of:

• Service, feeder, or branch-circuit demand at the time of peak loading.
• Supply voltage, phase configuration, and power factor when converting kW demand to current.
• Voltage drop at peak current, particularly on long feeder runs.
• Transformer, generator, switchgear, panelboard, and bus capacity.
• Motor starting, cyclic process loads, HVAC staging, electric heat, EV charging, or other coincident loads.
• Raceway routing and conduit layout when a capacity modification requires new feeder conductors.

For conductor sizing, a load factor does not replace the calculated load in amperes. The electrical design must separately establish the applicable load, circuit type, conductor ampacity, terminal rating, insulation temperature rating, adjustment factor, correction factor, and the number of current-carrying conductors. Raceway fill, AWG or kcmil conductor selection, equipment ratings, and installation conditions are separate determinations.

Field Verification

Use metered kWh and peak kW from the same service, feeder, or load point. Verify that the period hours match the energy accumulation period, including whether the period contains shutdowns, seasonal operation, holidays, or unusual production schedules.

The calculator’s arithmetic keeps Average demand visible, but it does not replace utility interval data, demand-history review, or equipment capacity evaluation. A favorable load factor cannot confirm that a service or feeder is adequate during the actual peak condition, and a low load factor does not identify the specific loads causing the peak. Review interval demand, operating schedules, measured current, voltage conditions, and applicable AHJ and equipment requirements before making a field or design decision.