Electrical calculators.
With the working shown.
Practical calculators for power, cables, energy and project planning. Select a calculator to see its scope and formulas.
Ohm’s law
Find voltage, current, resistance and power in a DC resistive circuit.
Watts to amps
Convert electrical input power to current, with an explicit supply type.
kW to amps
Convert kilowatts to amps for DC, single-phase or balanced three-phase.
Amps to kW
Calculate real electrical power from current, voltage and power factor.
kVA ↔ kW
Convert between apparent and real power using your power factor.
Electricity cost
Work out energy use and its cost from your own wattage and tariff.
EV charging cost
Calculate the energy charge for a session using grid-side kWh.
LED energy savings
Compare running energy and cost for two sets of lights.
Voltage drop
Calculate voltage drop using a supplied circuit coefficient, current and route length.
Prospective fault current
Compare line–neutral and line–earth fault-current estimates from separate loop impedances.
AWG to mm²
Convert American Wire Gauge to nominal conductor diameter and cross-sectional area.
Power factor correction
Calculate theoretical reactive compensation for a sinusoidal, lagging load.
Connected load
Add the electrical input power of equipment groups in watts and kilowatts.
Three-phase imbalance
Compare three RMS line currents using maximum deviation from their average.
R1 + R2
Calculate line and protective-conductor resistance from supplied resistance per kilometre.
Installation cost
Build a project subtotal from your own labour rate, materials and other costs.
Wire length
Total measured cable routes and parallel runs, with an optional length allowance.
Conduit cross-section
Compare round cable cross-sectional area with a conduit’s usable internal area.
Tray & trunking area
Compare round cable area with a specified rectangular containment cross-section.