Electrical engineering calculators
Engineering calculators for motors, transformers, cables, short circuit, earthing, generators, solar PV, batteries and airfield lighting. Each page states what the calculator does not cover, and whether independent reference values back it.
These calculators are built for electrical engineers, technicians, estimators and students. Every page shows the formula, a worked example with the steps written out, a table of typical values and the assumptions behind the result, so you can check the working against your standard or design basis. Results come from one tested engine, and you can open any calculator with your own values and print a calculation sheet.
Start with a category below, or pick a calculator by task. For simple unit changes such as kW to HP or psi to kPa, use the Conversion Centre. For quick everyday formulas such as amps to kW or Ohm's law, see the electrical conversions.
Browse by category
Electrical Fundamentals (29)Power and Energy (12)Cable Engineering (17)Motor Engineering (10)Transformer Engineering (7)Electrical Protection (6)Power Systems (9)Earthing and Grounding (5)Renewable Energy (5)Airport and AGL Engineering (14)Electronics and Instrumentation (12)Lighting and Facilities (13)Engineering Mathematics (30)
Motors
Motor Full-Load CurrentMotor Starting CurrentMotor Shaft TorqueInduction Motor SlipMotor Output Power and LossMotor Starting Voltage DipPump Shaft and Motor PowerStar-Delta Starting
Transformers
Transformer SizingTransformer EfficiencyTransformer Full-Load CurrentTransformer Voltage RegulationTransformer Loading
Short circuit
Cables
Cable Size for Voltage DropCable Derating and AmpacityAC Voltage DropCable Short-Circuit Withstand
Generators
Generator SizingGenerator Fuel Consumption
Earthing
Earth Rod ResistanceEarth Grid ResistanceNeutral Earthing ResistorEarth Rods in Parallel
Solar PV
Solar PV Array SizingSolar PV String SizeSolar PV Energy Yield
Batteries
Airport and AGL
AGL CCR LoadingAGL Isolating TransformerAGL Maximum Fittings per CircuitAGL CCR Input Power and EnergyAGL Brightness Step CurrentAGL Lamp Life at Circuit CurrentAGL Series Cable Loop LossAGL Series Cable Size for LossAGL Load with Failed LampsAGL Light Intensity at Distance
Ohm's Law
Capacitors and Reactive Power
Power Factor CorrectionCapacitors in Series and ParallelCapacitor Bank Size
Voltage Drop
Voltage DropMaximum Cable Length
Protection
DC Circuits
Resistors in SeriesResistors in ParallelDelta to Star Resistance Conversion
AC Circuits
Inductors in Series and ParallelInductive and Capacitive ReactanceSeries RLC ImpedanceFrequency and PeriodRMS, Peak and Peak-to-PeakLC Resonance and Q FactorCapacitor and Inductor Energy
Three Phase
Three-Phase PowerLine and Phase QuantitiesNeutral Current from Unbalanced LoadThree-Phase Voltage Unbalance
Cable and Wire
Cable ResistanceCable Power LossConductor Resistance vs TemperatureCopper vs Aluminium ConductorParallel Cable SetsSWG to Diameter and Area
Batteries and UPS
UPS Battery RuntimeBattery Series-Parallel BankBattery Charge Time
Power Systems
Per-Unit Base ValuesPer-Unit Base Conversion
EV Charging
Lighting
Lighting LevelLED Retrofit Savings and Payback
Harmonics
Short Circuit
Fault LevelFault Current by Fault Type
Electronics
LED Series ResistorRC Time Constant and CutoffDecibel ConverterOp-Amp GainRC Filter Cutoff
Instrumentation
4-20 mA Signal ScalingRTD Resistance to Temperature
Power and Energy
Conduit and Raceway
Converters and Units
HP to kW and kW to HPPower Unit ConverterEnergy Unit Converter
Industrial Electrical
Heater Power for Heating a LiquidFan and Pump Affinity Laws
Testing and Measurement
Insulation Resistance CorrectionPolarisation Index and DAR
Electrical Safety
Data Center Electrical
Data Centre PUERack Heat Load and Airflow
Renewable Energy
Semiconductor Components
Zener Shunt RegulatorTransistor Base Resistor555 Timer AstableHeatsink Thermal Resistance
Engineering Mathematics
Complex NumbersPhasor Sum and DifferencePercentage ErrorMean, Median and ModeStandard Deviation and VarianceQuadratic Equation SolverLogarithm CalculatorExponent and Root CalculatorPercentage CalculatorRatio CalculatorRounding and Significant FiguresFraction CalculatorSimultaneous Equations SolverLinear Interpolation CalculatorMatrix CalculatorVector CalculatorLinear RegressionPythagorean Theorem CalculatorTriangle CalculatorCircle CalculatorArea CalculatorVolume and Surface Area CalculatorSlope CalculatorDistance CalculatorProbabilityPermutations and CombinationsBinomial DistributionTrigonometry
General tools
Basic CalculatorScientific Calculator (standard and engineering, with complex numbers and phasors)