Electrical Calculators

Calculate the correct cable size for any circuit

Check voltage drop against BS 7671 limits

Cable sizing and circuit requirements for EV chargers

Cable sizing and protection for motor circuits

Cable sizing for lighting with inrush current

Cable size, MCB, diversity, and voltage drop for cooker circuits

Cable size, MCB, and voltage drop for electric shower circuits

Select the correct gland size for SWA cables

Cable size, MCB, and voltage drop for immersion heater circuits

Check if your installation needs a G98 notification or G99 application

Select the correct MCB type, rating, and RCD requirements for any circuit

Select the correct RCD type and sensitivity for any circuit

Cable sizing, MCB, and supply requirements for air source heat pumps

Calculate the correct cable size for your hot tub installation

Size the SWA supply cable for a garden office, workshop, or outbuilding with load estimation

DC & AC cable sizing, string configuration, and protection for solar PV

Size SWA cable from main board to sub-distribution board

Design a ring final circuit for 13A socket outlets

Calculate cable size for cooker circuits with BS 7671 diversity

Calculate emergency luminaire count, spacing, and battery sizing

Size fire alarm cables and check voltage drop per BS 5839-1

Select circuits and get a consumer unit size and protection recommendation

Calculate number of fittings needed using the lumen method

Size a domestic battery storage system with payback and electrical requirements

Maximum earth fault loop impedance values

Calculate prospective fault current (PFC)

Ring circuit continuity and Zs verification

Calculate R1+R2, Zs, and verify circuit compliance

Verify ADS compliance — check protective device disconnection time

Verify test results (Zs, IR, RCD) against BS 7671 limits

Check if upstream and downstream protective devices will discriminate

Maximum demand after diversity

Balance loads across three phases

Calculate total maximum demand after diversity for the EIC

Calculate capacitor bank size to improve power factor

Size UPS, generator, and battery for critical power

Size transformers, calculate fault levels, and select busbars

Calculate total load from smart home devices, PoE budget, and UPS sizing

Complete an EV charger electrical load assessment with supply adequacy check

CPC, main earthing and bonding conductor sizes

Check conduit and trunking cable capacity

Check cable capacity for trunking against BS 7671 45% fill limit

Calculate minimum CPC and earthing conductor size using S = √(I²t) / k

Convert kilowatts to amps for single and three-phase

Convert amps to kilowatts for single and three-phase

Calculate voltage, current, resistance or power

Convert between watts and amps

Convert between kVA and kW using power factor

Convert between AWG and metric mm² cable sizes

Calculate how much it costs to run any electrical appliance

Estimate labour and material costs for common electrical jobs

Calculate energy savings, payback period, and CO2 reduction from LED upgrades

Determine the correct VAT rate for electrical work and calculate invoice totals

Estimate job costs with regional rates, materials markup, and profit margin