Electrical Load Calculator
Create a preliminary electrical-load estimate from general loads, fixed heating, motor demand, diversity, startup demand and reserve capacity.
Default project preview
16.38 kW
Connected load
12.8 kW
Estimated current
75.8 A
Motor-start addition
3.6 kW
Apparent power
18.2 kVA
Calculator
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Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
General connected load
Enter this project assumption in W. The current imperial default is 6000 W.
Fixed heating and cooking load
Enter this project assumption in W. The current imperial default is 5000 W. Minimum: 0.
Largest motor running load
Enter this project assumption in W. The current imperial default is 1800 W. Minimum: 0.
Motor starting multiplier
Enter this project assumption in ×. The current imperial default is 3 ×. Minimum: 1.
Non-motor demand factor
Enter this project assumption in %. The current imperial default is 75 %. Minimum: 1. Maximum: 100.
Planning reserve
Enter this project assumption in %. The current imperial default is 20 %. Minimum: 0. Maximum: 50.
System voltage
Enter this project assumption in V. The current imperial default is 240 V.
Number of phases
Enter this project assumption in 1 or 3. The current imperial default is 1 1 or 3. Minimum: 1. Maximum: 3.
Planning power factor
Enter this project assumption in a unitless value. The current imperial default is 0.9. Minimum: 0.1. Maximum: 1.
Average loaded hours
Enter this project assumption in hours/day. The current imperial default is 6 hours/day. Minimum: 0. Maximum: 24.
Electricity price
Enter this project assumption in per kWh. The current imperial default is 0.18 per kWh. Minimum: 0.
How to read the outputs
Connected load
before diversity. Default preview: 12.8 kW.
Estimated current
1-phase at 240 V. Default preview: 75.8 A.
Motor-start addition
3× starting multiplier. Default preview: 3.6 kW.
Apparent power
power factor 0.9. Default preview: 18.2 kVA.
Daily energy guide
6 loaded hours. Default preview: 60.3 kWh.
Daily energy cost
diversified running load. Default preview: $10.85.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Diversified demand = non-motor connected load × demand factor + motor running load. Peak capacity adds motor starting demand and reserve. Current depends on voltage, phases and power factor.
Reviewed project guidance
How to use this estimate in a real project
Last reviewed: July 29, 2026
This calculator totals entered electrical loads and applies user-supplied demand assumptions for preliminary planning. It does not perform a code-compliant service, feeder or branch-circuit calculation.
Calculation steps
- 1List connected loads in consistent watts or volt-amperes.
- 2Separate continuous, intermittent and noncoincident loads.
- 3Apply only verified demand factors.
- 4Convert final apparent power to current for the actual voltage and phase system.
Worked numerical example
A group of loads totaling 18,000 W at 240 V represents 75 A before demand factors and power-factor effects. Continuous and noncoincident loads must then be treated according to the applicable design method.
Purchasing and rounding
The output is not a breaker, conductor or panel selection. Standard equipment ratings require coordinated conductor ampacity, overcurrent protection, fault current and installation conditions.
Interpret the result
Connected load is the sum of nameplates; calculated demand may be lower when an accepted method permits diversity. Neither value alone proves available capacity.
Page-specific assumptions
- Entered ratings are accurate.
- Voltage and phase are correct.
- Demand factors are user-supplied and applicable.
- Power factor and starting current are addressed separately when relevant.
Common mistakes
- Adding amperes from different voltages.
- Using watts and VA interchangeably for all loads.
- Ignoring continuous-load treatment.
- Selecting service size from this estimate without a qualified calculation.
Primary and technical references
BuildMeter provides planning estimates, not engineering, architectural, electrical, mechanical, plumbing, permit or code approval. Review the methodology and verify final decisions with product documentation and qualified professionals.
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Electrical Load Calculator questions
Is connected load the same as demand load?+
No. Connected load totals nameplate loads, while demand estimates which loads are likely to operate together under applicable rules.
Why include motor starting demand?+
Motors and compressors can draw substantially more power during startup than while running.
Can this size a breaker or electrical service?+
No. Electrical sizing must follow applicable code and equipment data under a qualified designer or electrician.