Tax Tool

Energy

Simultaneous Demand Tool

Estimate the peak electricity demand of appliances used at the same time. Enter your usage and energy price for a planning estimate.

Quick math0

Use this for quick arithmetic, percentages, or to check figures while filling in the main tool, without leaving the page.

Your figures

Estimate

Estimated simultaneous demand: 3.50 kW

Estimated demand
3.50 kW
Current at 230 V, single-phase
15.2 A

Simple estimate. Actual coincidence and supply capacity depend on appliances and the electrical installation.

How to use this tool

  1. Use Simultaneous Demand Tool for the question described above, and check that the inputs match your records and time period.
  2. Enter combined appliance power (Power of appliances that may run at once.).
  3. Enter simultaneous use (Estimated share running at the same time.).
  4. Change combined appliance power, simultaneous use to compare scenarios, then check the units in the result.

Worked example with the prefilled values

This example shows how Simultaneous Demand Tool uses its starting values. Change the calculator inputs to estimate your own situation.

Combined appliance power
5000 W
Simultaneous use
70 %

Estimated simultaneous demand: 3.50 kW

  • Estimated demand3.50 kW
  • Current at 230 V, single-phase15.2 A

Simple estimate. Actual coincidence and supply capacity depend on appliances and the electrical installation.

Formula and calculation logic

Estimated simultaneous demand (kW) = combined appliance power (W) ÷ 1,000 × simultaneous-use percentage ÷ 100

Illustrative single-phase current (A) = demand (kW) × 1,000 ÷ 230 V

Combined appliance watts are converted to kilowatts and multiplied by the simultaneous-use percentage. The amp figure divides the estimated power by 230 volts for a single-phase illustration.

Assumptions

  • The simultaneous-use percentage is your estimate. Starting current, three-phase wiring, voltage drop, and circuit protection are not modeled.

Published sources

Further reading for checking current rules and information. These links are not live inputs to the tool.

Questions about this tool

What does the simultaneous-use percentage change?

It estimates how much of the connected appliance load is running at once. Increase it for appliances likely to overlap; it is not a substitute for checking the circuit design.