Electrical demand load calculator

Enter the sum of the connected equipment loads, choose the same unit used by that sum, and provide the applicable demand factor as a percentage. The result shows the calculated demand load and the reduction from the connected total. It is a transparent arithmetic tool for engineers, estimators, contractors, and reviewers who already know which demand factor their governing code or project criteria require.

Start with a defensible connected-load total

The calculation begins with the total connected load: the sum of the nameplate or design loads that are included in the service calculation before diversity is applied. Keep every value in one consistent unit before adding it. For example, do not combine watts and kilowatts without conversion, or amperes and kilovolt-amperes as though they represented the same quantity. This calculator preserves the unit you select; it does not convert between real power, apparent power, and current because those conversions require additional facts such as voltage, phase configuration, and power factor. Confirm the scope of the connected total as well. A total for an entire building is not interchangeable with a panel total, feeder total, tenant total, or a particular load category. Document which equipment is included, which loads are continuous, and whether any mutually exclusive loads have already been treated elsewhere. A reliable diversified result depends on a connected-load input that is complete, consistently measured, and appropriate to the exact service or feeder being evaluated.

Apply the demand factor correctly

A demand factor represents the portion of connected load expected to contribute to the design demand under the applicable calculation method. Enter it as a percentage, not a decimal fraction: enter 80 for eighty percent, not 0.8. The calculator multiplies the total connected load by that percentage divided by 100. A connected load of 125 kVA with an 80 percent factor therefore produces a diversified demand load of 100 kVA and a demand reduction of 25 kVA. The accepted range is greater than zero through 100 percent. Choosing the factor is an engineering and code-compliance decision, not something the calculator can infer from the load total. Demand factors may differ by occupancy, equipment category, quantity, operating pattern, jurisdiction, and code edition. Some rules use stepped tables or apply different factors to separate portions of a load. In those cases, calculate each applicable block independently and combine the resulting demand loads as the governing method directs instead of applying one blended factor without support.

Use the result in service sizing

Treat the diversified demand load as an input to a broader service-sizing workflow, not as a final equipment rating by itself. The returned value remains in the selected input unit, so 100 kVA is an apparent-power demand and 100 A is a current demand; the two cannot be exchanged without the relevant electrical system data. After calculating demand, apply every additional requirement that governs the installation. Depending on the project, those requirements can include continuous-load multipliers, motor provisions, heating and cooling noncoincident rules, future capacity, voltage and phase conversion, power factor, standard equipment ratings, conductor ampacity, temperature and bundling adjustments, overcurrent protection, and utility criteria. Preserve the connected load, factor source, code edition, assumptions, and calculator output in the design record so another reviewer can reproduce the arithmetic. If a local authority, utility, project specification, or licensed professional requires a different method, that requirement controls. The calculator makes the multiplication consistent and auditable, while responsibility for selecting inputs and completing the design remains with the qualified designer.