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.
Get StartedAppliances
Appliance 1
Appliance 2
Appliance 3
Load Calculation Results
Effective W = Wattage × Quantity × (Hours ÷ 24)
Total Load = Σ Effective W | kW = W ÷ 1000
kVA = kW ÷ Power Factor
Total Effective Load
0 W
Real Power
0.00 kW
Apparent Power
0.00 kVA
All calculations are estimates and should be verified by a professional.
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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Book a Free DemoTypical Appliance Loads & Benchmarks
Use these common values as starting points; replace with actual appliance ratings when available.
LED light
8-12 W per unit
Ceiling fan
60-120 W
Split AC (1.5-2.0 TR)
1.2-2.2 kW each
Water heater (resistive)
2-4 kW
Electric oven
2-5 kW
EV home charger (Level 2)
3.3-7.2 kW
Refrigerator
0.1-0.4 kW (running)
These benchmarks help electricians and facility managers validate whether calculated service sizes are reasonable.
Frequently Asked Questions
What's the difference between connected load and demand load?
Connected load is the sum of all rated appliance power. Demand load adjusts connected load by a demand factor to reflect realistic simultaneous usage.
What is diversity factor and when should I use it?
Diversity factor accounts for non-simultaneous peaks across sub-circuits or areas; use it when multiple zones share a service to reduce conservative sizing.
How do I select the right demand factor?
Use typical industry defaults (residential 50-75%) or historical meter data for precise selection. Err on the side of caution for critical systems.
Does this calculator size wire gauge and breakers?
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.
Can I use this for generator or UPS sizing?
Yes—use the diversity-adjusted peak load plus starting currents for motors and inrush to size backup power.
How do motor starting currents affect load calculations?
Motors draw higher inrush currents at start. Include starting multipliers (e.g., 3-8× motor rated current) for circuits feeding motor loads.
Should I include future expansion in the calculation?
Yes—add a percentage allowance (e.g., 10-25%) for planned expansion to avoid under-sizing service.
Is power factor important?
For commercial/industrial installations, yes. Low power factor increases apparent power (kVA) and affects transformer and generator sizing.