Electrical calculators that work on site
Free tools for UK electricians and apprentices. Type two values into Ohm's law here, or pick a calculator below.
Most used: cable sizing, voltage drop, CPC size.
Works offline. On your phone, use Add to Home Screen to keep it with your other apps.
V
A
Ω
W
Enter any two values
–
Voltage–
Current–
Resistance–
Power–
All calculators
- Ohm's lawFind voltage, current, resistance or power from any two.Open
- Power and currentConvert kW to amps and back, single or three phase.Open
- Voltage dropCheck a cable run against the 3 % and 5 % limits.Open
- Cable sizingTwin and earth size from device rating, install method and derating, with a voltage drop check.Open
- CPC size (adiabatic)Minimum protective conductor size for a fault.Open
- Conduit and trunking fillHow many cables fit.Coming soon
- Maximum ZsEarth fault loop limits for common devices.Coming soon