Introduction #

When this guide fits: You have a peak demand from the utility (or MSB meter) and an average kW from production logs or EMS—and need load factor to judge transformer utilisation, energy cost, or whether a generator runs efficiently.

When it is not suitable: Branch circuit ampacity or motor starting protection—use NEC/IEC branch rules and Motor Starting & Protection instead.

Load factor is not the same as diversity factor or demand factor. This guide defines all three, shows a numeric example on the same 491 kW peak plant used in Connected vs Demand Load, and links to Factory Load Calculator and Power Calculator hub.

Definitions — three factors people mix up #

Term Formula (concept) What it answers
Connected load Sum of nameplate kW Inventory ceiling if everything ran at once
Demand / peak load Metered maximum kW (billing window) What sizes mains and transformer kVA
Diversity factor Connected ÷ coincident demand How much simultaneous overlap you assume
Load factor (LF) Average kW ÷ Peak kW (same period) How flat the load profile is over time

Load factor uses time: average power divided by peak power over the same interval (often monthly or annual).

Load factor formula #

Load factor = Average load (kW) ÷ Peak load (kW)

  • Result is a decimal (0–1) or percentage.
  • LF → 1.0 means the plant runs near peak most of the time (high utilisation, higher energy intensity per kW of installed capacity).
  • Low LF means large peaks with long idle periods—common in batch plants; affects energy cost per unit and generator fuel more than peak kVA sizing.

Related energy screening: Industrial Energy Estimator.

Worked example — packaging plant #

From Connected vs Demand Load:

Metric Value
Connected load 682 kW
Peak demand (15-min utility) 491 kW
Average load (same billing month, EMS) 318 kW

Load factor:

  • LF = 318 ÷ 491 ≈ 0.65 (65%)

Interpretation:

  • Transformer sized on 491 kW peak is correct for thermal/inrush limits.
  • LF 0.65 tells operations the plant is not flat-loaded—off-peak efficiency and tariff structures (demand + energy charges) should use both numbers.
  • Do not size the main transformer on 318 kW average alone—you would underrate for peak.

Convert peak kW to kVA for equipment: kW to kVA Calculator → Transformer Size Calculator.

How engineers use load factor #

Use case Action
Transformer utilisation review Compare peak kVA to nameplate; LF explains why utilisation looks low on paper
Generator fuel screening Low LF on backup load may still need peak kVA sizing, but runtime fuel follows average kW
Energy cost budgeting Energy Estimator with average kW × hours
Expansion planning Falling LF after adding machines may signal scheduling opportunity before upsizing transformer

Common mistakes #

  1. Using LF instead of peak for breaker and transformer peak sizing.
  2. Confusing LF with diversity factor (682/491 = 1.39 is diversity, not LF).
  3. Mixing intervals—monthly average with a single-day peak invalidates LF.
  4. Ignoring PF when converting kW peaks to kVA for transformer frames.

Next steps #

  1. Roll up equipment in Factory Load Calculator.
  2. Separate connected vs demand in Connected vs Demand Guide.
  3. Apply diversity assumptions in Diversity Factor Guide.
  4. Size transformer: Factory Load vs Transformer Size.
  5. Protection handoff: Electrical Calculator hub.

FAQ #

What is a good load factor for a factory?

There is no universal target—0.55–0.75 is common on mixed production lines. Compare against your own history and tariff; use peak kW for equipment sizing regardless of LF.

How is load factor different from demand factor?

Demand factor relates connected load to maximum demand. Load factor relates average load to peak demand over time. Both can appear on the same project spreadsheet for different decisions.

Can I enter load factor in the Factory Load Calculator?

The tool assumes simultaneous-use inputs unless you reduce counts or kW for diversity. Compute LF offline from meter data, then use peak kW from the calculator or utility for sizing paths.

Does low load factor mean I can downsize the transformer?

Not automatically. Peak demand still sets thermal and protection limits. Low LF mainly informs energy economics and operating strategy, not peak kVA by itself.

Where does load factor affect generator sizing?

Generator kVA must cover peak critical load. Fuel and runtime estimates lean on average kW—use Generator Size Calculator for kVA and Generator + UPS Calculator when bridge minutes matter.