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A wall-mounted electric vehicle charger with a glowing status light charging a car in a garage at night while snow falls outside

Calculator · Drawing E-503

EV charging time calculator

How long it takes to add range or fill a battery at home on Level 1 or Level 2, given the charger’s current setting and your car’s onboard charger limit.

EV charging time · E-503Metric
km
kWh/100 km
From the car’s trip computer or spec sheet. Cold weather raises it.
kWh
kW
The most AC power the car accepts.
%
An assumption: some energy is lost as heat. Adjust to your car.
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Estimates only. Real charging time varies with temperature, state of charge and the car’s charging curve.

CCT 01How it works

AC charging power is the lower of the charger’s output (volts × amps) and the car’s onboard charger limit. Time is the energy you want to add divided by that power, allowing for losses:

hours = energy to add ÷ (charging power × efficiency)

If you enter kilometres, energy = kilometres × consumption ÷ 100.

CCT 02Assumptions and limits

  • The efficiency figure is an assumption you can change. Charging losses and battery heating vary by car and temperature.
  • In deep cold, a car may spend energy warming its battery before and during charging. Calgary’s January design temperature is -30 °C1, so winter sessions run longer than this estimate.
  • A charger is a continuous load, so the circuit and breaker are sized above the charger’s current. The installation manual states what it needs. In Calgary, EV-charger wiring needs a contractor permit23.
  • A charger whose current setting a user can change without an electrician counts at its maximum in the load calculation4.

Questions people ask

Is Level 1 charging enough in Calgary?

For short daily commutes it can be, overnight. Run your own commute through the calculator above. In winter the car uses more energy per kilometre and may warm its battery, so Level 1 falls behind sooner.

What size charger do I need?

Enough to refill your typical day overnight, within what your panel can carry. A higher setting does not help if the car’s onboard charger is the limit. Check your service with the load calculator, and read EV charging at home.

Do I need a permit for an EV charger in Calgary?

Yes. An EV charger needs an electrical permit, and the wiring must be done under a contractor permit rather than a homeowner permit. See EV charger installation.

Sources

  1. National Building Code - 2023 Alberta Edition, Volume 1, Division B, Appendix C, Table C-2 Climatic Design Data for Selected Locations in AlbertaAlberta Municipal Affairs / National Research Council of Canada · 2023 Alberta Edition, second printing incl. revisions and errata released April 2026
  2. Homeowner electrical and plumbing permitsCity of Calgary · retrieved 2026-09-25
  3. Electrical permits for contractorsCity of Calgary · retrieved 2026-09-25
  4. STANDATA interpretation 24-ECI-086 Electric vehicle charging systemsAlberta Municipal Affairs · April 2025