Electrical & Wiring Calculators
Our electrical and wiring calculators help you size cables correctly, check voltage drop compliance, pick the right breaker and plan conduit runs — based on BS 7671 (IET Wiring Regulations) and US NEC practice.
Whether you are running a new ring main, adding a cooker circuit, or wiring outdoor lighting, these tools take the guesswork out of cable selection by factoring in installation method, ambient temperature, circuit grouping and cable run length.
Electrical Calculators(5)
Cable Size Calculator (UK)
This cable size calculator UK tool works out the minimum cable size you need from the voltage drop, current load, cable run length and installation method, following BS 7671 (IET Wiring Regulations 18th Edition). Supports Twin & Earth and SWA cables.
Cable Length Calculator
Work out how many metres or feet of electrical cable you need for a job. Add multiple cable runs, pick the circuit type, and get a total length with waste allowance — so you buy the right reel size first time.
Voltage Drop Calculator
Calculate the voltage drop and percentage loss along a cable run from the conductor size, current and length, for both UK and US wiring.
Breaker Size Calculator
Work out the correct circuit breaker or fuse rating (MCB / breaker) for a load from its power, voltage and continuous-load factor.
Conduit Fill Calculator
Check how many cables or conductors fit in a conduit and the percentage fill against the 40% maximum, for UK and US conduit sizes.