House Electrical Demand Calculator

Ontario Residential Calculator

House Electrical Demand Calculator

Estimate the electrical demand and potential minimum service size for a single dwelling with a 120/240 V electrical service.

Home Size

Enter the total finished living area of the house.

Total living area Area unit

Include the basement only when it forms part of the finished living area used for the demand calculation.

Heating & Cooling

Enter electrical input ratings, not heating or cooling output capacity.

Electric space-heating load

Enter 0 for gas, oil or propane heating with no major electric heat. Air-conditioning load

Use the electrical nameplate input, not the unit’s BTU rating.

Heating and cooling can operate simultaneously Leave unchecked when approved controls or interlocking prevent simultaneous operation.

Range & Water Heating

Add the nameplate ratings of the installed equipment.

Electric range rating

Leave at 0 when there is no electric cooking range. Tankless water heater / water steamer

Do not enter a regular storage-tank heater here.

Electric Vehicle Charging

Add an existing or proposed EV charger.

EV charger output current Custom EV charger current

EV charging voltage Energy-management arrangement Maximum EV load permitted by the management system

Enter the maximum load established by the approved energy-management system.

Energy-management selections must be confirmed against the approved equipment, control settings and installation design.

Other Major Loads

Select common equipment and adjust the ratings where necessary.

Electric clothes dryer

Storage-tank water heater

Hot tub or spa

Pool equipment or heater

Sauna or steam generator

Other load over 1,500 W

The displayed values are examples only. Replace them with actual nameplate ratings whenever available.

Preliminary Result

Estimated Electrical Demand

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Total calculated load —

Calculated demand —

Indicated service category —

Calculation Breakdown

Basic floor-area load —

Heating and cooling —

Electric range —

Tankless water heating —

EV charging —

Other major loads —

Important: This calculator provides a preliminary estimate only. It does not replace an electrical design, permit calculation, utility review or inspection. Final load calculations, service sizing and equipment selection must be verified by a qualified electrical professional in accordance with the current Ontario Electrical Safety Code and applicable utility requirements.

House Electrical Demand Calculator