Electrical

Electrical calculators built for controls work.

Power, motor, conductor, transformer, and protection sizing references for automation engineers, electricians, technicians, and panel troubleshooters.

Electrical Calculator Index

Core electrical math for controls troubleshooting, panel review, field estimates, and early design checks. Final installation decisions still need manufacturer data, site standards, and applicable code review.

Live recalculation

Ohm's LawCurrentPowerEnergyPower FactorMotor FLAMotor SpeedVoltage DropWire SizeTransformerFuse SizingBreaker Sizing

Ohm's Law

Solve voltage, current, resistance, and power when at least two values are known.

VoltageVCurrentAResistanceohmPowerW

Voltage

120 V

Current

5 A

Resistance

24 ohm

Power

600 W

Formula

I = V / R, P = V^2 / R

Single / Three Phase Power

Calculate kW, kVA, and kVAR from voltage, current, phase, and power factor.

PhaseVoltageV L-LCurrentAPower factorUse decimal form, such as 0.85.

Real power

7.067 kW

Apparent power

8.314 kVA

Reactive power

4.38 kVAR

Power factor

0.85

Formula

kW = sqrt(3) * VLL * I * PF / 1000

Current

Estimate line current from real power, voltage, phase, and power factor.

PhaseVoltageV L-LReal powerkWPower factor

Load current

10.613 A

Apparent power

8.824 kVA

Formula

I = kW * 1000 / (sqrt(3) * VLL * PF)

Energy

Convert load power and runtime into kWh and optional operating cost.

Real powerkWRuntimehoursCost$/kWh

Energy

20 kWh

Estimated cost

Formula

kWh = kW * hours

Power Factor

Calculate PF, phase angle, and reactive power from kW and kVA.

Real powerkWApparent powerkVA

Power factor

0.8

Power factor percent

80%

Phase angle

36.87 deg

Reactive power

9 kVAR

Formula

PF = kW / kVA

Motor FLA

Estimate running current from HP, voltage, phase, efficiency, and power factor.

PhaseHorsepowerHPVoltageV L-LEfficiency%Power factor

Estimated FLA

5.86 A

Output power

3730 W

Input power

4.144 kW

Formula

FLA = HP * 746 / (sqrt(3) * V * efficiency * PF)

Estimated running current from nameplate-style values. Use manufacturer data or applicable motor tables for final conductor and protection sizing.

Motor Speed

Calculate synchronous RPM and estimated running speed from frequency, poles, and slip.

FrequencyHzPolesSlip%

Synchronous speed

1800 RPM

Estimated actual speed

1746 RPM

Slip speed

54 RPM

Formula

Synchronous RPM = 120 * Hz / poles

Transformer Calculations

Estimate primary and secondary current from transformer kVA and voltage.

PhaseTransformer sizekVAPrimary voltageVSecondary voltageV

Primary current

90.21 A

Secondary current

208.18 A

Voltage ratio

2.308:1

Formula

I = kVA * 1000 / (sqrt(3) * V)

Voltage Drop

Estimate voltage drop by phase, conductor material, conductor size, current, and one-way length.

PhaseMaterialConductorVoltageV L-LCurrentALengthft one-wayParallel sets

Voltage drop

13.687 V

Voltage drop percent

2.851%

Ending voltage

466.313 V

Conductor basis

12 AWG / 6530 CM

Formula

VD = sqrt(3) * K * I * D / CM

Wire Size

Recommend a conductor size from voltage-drop target only.

PhaseMaterialVoltageV L-LCurrentALengthft one-wayMax drop%Parallel sets

Recommended conductor

12 AWG

Required circular mils

6207 CM

Recommended circular mils

6530 CM

Max drop

14.4 V

Voltage-drop recommendation only. Confirm ampacity, derating, terminals, insulation, conduit fill, and local code requirements.

Fuse / Circuit Breaker Sizing

Apply configurable multipliers and round up to common overcurrent device sizes.

Load currentAFuse multiplier%Breaker multiplier%

Fuse required

33.75 A

Fuse standard size

35 A

Breaker required

33.75 A

Breaker standard size

35 A

Formula

Minimum rating = load current * multiplier

Reference sizing only. Final fuse or breaker selection depends on equipment rules, fault current, conductor protection, motor starting, and applicable codes.