Electrical Load Calculator
Create a simple panel load schedule and calculate connected load, demand load, kVA, panel current, spare capacity and feeder load.
โก Field Rule: Size panels, feeders, breakers and generator/UPS input from the demand load, but always check local code, continuous-load rules, motor starting current and utility requirements. Use this with the Voltage Drop Calculator, Breaker Size Calculator, UPS Size Calculator and Generator Size Calculator.
๐ Panel Load Schedule: circuits โ demand load โ panel current
System Phase
Voltage
Panel Rating
Spare Capacity Target
| Load / Circuit | Qty | Value | Unit | PF | Demand % | Action |
|---|
Schedule presets:
Enter each load as W, kW, VA or kVA. Demand % handles diversity. For motors and large nonlinear loads, confirm sizing with local code and manufacturer data.
Total Load
Power Factor
Demand Factor
System Phase
Voltage
Spare Margin
Quick presets:
Load Value
Power Factor if kW/W
System Phase
Voltage
Continuous Load Factor
Recommended Spare
Feeder presets:
๐ Formula Reference
Connected Load
Connected W = ฮฃ(qty ร load W)
Demand Load
Demand W = Connected W ร Demand Factor
Single Phase Current
I = VA รท V
Three Phase Current
I = VA รท (โ3 ร V)
๐ Quick Reference
Common PF
Heating1.0
Lighting LED0.85โ0.95
Motors0.75โ0.9
Spare Capacity
Minimum practical10%
Good target20%
Future expansion30%
Voltage Examples
KSA common 1ฯ220โ230V
3ฯ LV400โ415V
US 3ฯ208/480V
๐ Design Notes
Connected load is not always demand loadA load schedule separates installed load from expected running load. Demand factor prevents oversizing when all loads are not used at the same time.
Use VA for panel currentBreakers, panels and feeders carry current, so convert kW to kVA using power factor before calculating amps.
Motor panels need starting checksFor motor-heavy panels, check starting current, voltage drop, VFD/soft starter needs and breaker coordination separately.
Local code comes firstThis calculator is a field estimate. Final panel and cable sizing must follow local electrical code and project specifications.
What is an Electrical Load Calculator?
An electrical load calculator estimates total connected load, demand load, kVA and panel current for a distribution board, MCC, sub-panel or feeder. It is useful for preparing a simple load schedule before selecting panel rating, breaker size, cable size, UPS or generator capacity.
How to calculate panel load schedule
List each circuit load, quantity, power factor and demand percentage. Convert each load into watts and VA, then add the totals. Finally calculate current using single-phase or three-phase current formulas.
What is demand factor in electrical load calculation?
Demand factor is the percentage of connected load expected to run at the same time. For example, 20 kW connected load at 80% demand becomes 16 kW demand load.
โ Frequently Asked Questions
Add the connected load of every circuit, apply demand or diversity factor, convert kW to kVA using power factor, then calculate panel current from voltage and phase.
Connected load is the total installed load. Demand load is the realistic load after applying demand factor because all loads usually do not run together.
Use kVA = kW รท power factor. Example: 20 kW at 0.8 PF equals 25 kVA.
Use I = kVA ร 1000 รท (1.732 ร line voltage). Example: 50 kVA at 415V three phase is about 69.6A.
Many practical designs keep 20% spare capacity, but the right value depends on future expansion, project specification and local code.
For energy or real power, kW is useful. For current, panel, cable, transformer, UPS and generator sizing, kVA is usually more important because it includes power factor.
Use current = VA รท voltage. If your load is in watts, convert to VA first using VA = W รท PF.
It gives the load current. Cable size also depends on installation method, ambient temperature, grouping, voltage drop, fault level and local standards. Use a cable size or voltage drop calculator next.
Use motor input kW or FLA where possible, include realistic demand, and separately check starting current, voltage drop and protection coordination.
They are closely related in practical load calculations. Demand factor is demand load divided by connected load. Diversity considers that different loads peak at different times.