Load Factor, Demand Factor, Diversity Factor and Capacity Factor Calculator

Work out the factors that describe how a load or a power plant is used, and what a two-part tariff costs.

Calculated from standard textbook formulas, with every step shown. The formulas are fixed, so the working does not need checking: what matters is the numbers you type in. Use these calculators only if you are competent to choose the inputs (loads, material strength, dimensions, supports) and check your units and assumptions. For learning and checking your own working: design and sign-off are for a qualified engineer. Drafting Central does not store the numbers you type.

How this calculator works

Enter the maximum demand, the connected load, the energy used, the length of the period and the installed capacity. Optionally add the sum of the separate maximum demands of a group of loads.

The calculator gives the average demand, the load factor (average over maximum demand), the demand factor (maximum demand over connected load), the capacity factor, the utilisation factor and the diversity factor.

Enter the demand and energy charges to get the bill for the period under a two-part tariff and the average cost of each kWh.

Formulas used

  • \mathrm{LF} = \frac{E/T}{P_{max}}
  • \mathrm{DF} = \frac{P_{max}}{\text{connected load}}
  • \mathrm{CF} = \frac{E}{\text{capacity}\times T}
  • \mathrm{DiF} = \frac{\sum P_{max,i}}{P_{max,group}}

Worked example

With the default numbers in the calculator above:

  1. Average demand over the period: 500.00 kW
  2. Load factor: 62.50 %
  3. Demand factor: 53.33 %
  4. Capacity (plant) factor: 50.00 %
  5. Utilisation (use) factor: 80.00 %
  6. Diversity factor: 1.38 (it is never below 1)
  7. Bill for the period: demand charge and energy charge: $52800.00 (demand charge $9600.00, energy charge $43200.00)
  8. Average cost of each kWh: $0.15 per kWh

Change the numbers in the calculator to see the full working, every step, for your own case.

Common questions

What is a good load factor?

The closer to 1 the better, because the supply is used evenly. Many commercial buildings are 40 to 60 percent. A low load factor means high cost per kWh.

What is the difference between demand factor and load factor?

Demand factor compares the peak with the total connected load. Load factor compares the average with the peak.

Why is the diversity factor always 1 or more?

The separate peaks of the loads do not all happen together, so the peak of the whole group is less than the sum of the separate peaks.

What is a two-part tariff?

A charge for the maximum demand (the capacity you require the supplier to hold) plus a charge for the energy you actually use.

Related calculators

Got a question about this? Ask an engineering question and get a plain-language answer with references.

Further reading: Any power system text (Wadhwa, Electrical Power Systems; Weedy, Electric Power Systems; chapters on tariffs and load curves).

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