Electrician Calculators
The most useful calculators and tools for electricians.
14 tools · Top 14 most used · 100% Free
Everyday sparky maths — sizing conductors, converting between power units, and checking loads before you pull a cable or sign off a job. The tricky part is matching the calculator to what you actually know: whether you're working from watts, amps, kVA or resistance, and whether the circuit is single- or three-phase changes which tool gives you a trustworthy answer. Treat all outputs as estimates for planning and cross-check against the relevant wiring rules and manufacturer data before installing.
Power, current & unit conversions
Start here when you have one quantity (watts, amps, kVA or power factor) and need another to size a supply or check a load. Use the three-phase tool for motors and distribution boards rather than the single-phase watts/amps converters.
Cable sizing & voltage drop
Reach for voltage drop when a run is long or a load is heavy and you need to confirm the conductor is large enough; pair it with Ohm's Law to sanity-check current and resistance on the circuit.
Resistor & small-signal circuits
For control gear, boards and LED work: combine resistors in series or parallel to hit a target value, and use the LED tool to pick the correct current-limiting resistor.
Energy, running costs & batteries
Use these when a client asks what an appliance costs to run, or when sizing battery-backed or DC systems from amp-hour and watt-hour figures.
Common tasks
- Convert appliance watts to the amps a circuit will draw
- Check voltage drop on a long cable run
- Size a three-phase supply for a motor or board
- Pick a current-limiting resistor for an LED
- Estimate an appliance's running cost in kWh
- Work out battery runtime from amp-hour capacity
Top 14 Calculators for electricians
Ohms Law Calculator
Core electrical calculations
Use Calculator2Voltage Drop Calculator
Electrical basics
Use Calculator3Watts to Amps Calculator
Electrical basics
Use Calculator4Amps to Watts Calculator
Electrical basics
Use Calculator5kVA to kW Calculator
Electrical basics
Use Calculator6Power Factor Calculator
Electrical basics
Use Calculator7Three Phase Power Calculator
Electrical basics
Use Calculator8Watt-hours to Amp-hours Calculator
Electrical basics
Use Calculator9Watts to kWh Calculator
Energy & running costs
Use Calculator10Electricity Cost Calculator
Energy & power
Use Calculator11Parallel Resistance Calculator
Circuits
Use Calculator12Series Resistance Calculator
Circuits
Use Calculator13LED Resistor Calculator
Circuits
Use Calculator14Battery Life Calculator
Batteries & power
Use Calculator