Electricity Load Calculator
Use our free electricity load calculator to quickly estimate connected load, diversity-adjusted peak load, and required breaker/circuit capacity, based on key inputs like appliances, quantities, hours of use, and demand/diversity factors. Perfect for homeowners, electricians, and facility managers.
Electricity Load Formula
Estimating connected and peak loads ensures you size service entries, wires, breakers, and generation backup correctly. It prevents overloads, reduces risk, and helps plan for future expansion.
How this electricity load calculator works
This calculator sums the rated power of all listed appliances to get connected load, applies a demand factor to reflect that not all devices run simultaneously, and applies diversity where appropriate to estimate realistic peak demand. It converts power into current based on supply voltage and suggests service sizes. Use the optional power factor and expansion allowance for more accurate commercial or industrial sizing.
When to use this electricity load calculator
When planning a new residential or commercial electrical service
For sizing main breaker, distribution panels, and wire gauge
To estimate generator or UPS capacity needs
While planning electrification or adding high-load appliances (EV charger, HVAC)
For energy budgeting and estimating monthly kWh consumption
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Typical Appliance Loads & Benchmarks
Use these common values as starting points; replace with actual appliance ratings when available.
LED light
Ceiling fan
Split AC (1.5-2.0 TR)
Water heater (resistive)
Electric oven
EV home charger (Level 2)
Refrigerator
These benchmarks help electricians and facility managers validate whether calculated service sizes are reasonable.
Frequently Asked Questions
Connected load is the sum of all rated appliance power. Demand load adjusts connected load by a demand factor to reflect realistic simultaneous usage.
Diversity factor accounts for non-simultaneous peaks across sub-circuits or areas; use it when multiple zones share a service to reduce conservative sizing.
Use typical industry defaults (residential 50-75%) or historical meter data for precise selection. Err on the side of caution for critical systems.
It provides suggested current (A) and service sizes. Final wire and breaker sizing must follow local electrical codes and safety margins—consult a licensed electrician.
Yes—use the diversity-adjusted peak load plus starting currents for motors and inrush to size backup power.
Motors draw higher inrush currents at start. Include starting multipliers (e.g., 3-8× motor rated current) for circuits feeding motor loads.
Yes—add a percentage allowance (e.g., 10-25%) for planned expansion to avoid under-sizing service.
For commercial/industrial installations, yes. Low power factor increases apparent power (kVA) and affects transformer and generator sizing.