Estimates the connected and diversified load of a bank of identical EV charge points and the resulting supply current (single- or three-phase).
Design-aid only. Verify the maximum demand and final circuit design to BS 7671 Section 722.
For design guidance only. Always verify with a qualified engineer.
About this EV charger load calculator
This free EV charger load & demand calculator estimates the connected and diversified electrical load of a bank of identical electric-vehicle charge points, and the resulting supply current for a single- or three-phase connection. It is aimed at electrical designers, contractors and facilities engineers sizing the supply, distribution board, cabling and protection for domestic, workplace and depot charging at tender or verification stage. Everything runs in your browser. Nothing is uploaded.
How EV charger load is calculated
Connected power is simply Pconn = N × Pcharger (number of points times rated power per point). The diversified demand applies your diversity factor to that sum: Pdiv = Pconn × DF. Supply current then follows standard AC power theory: the per-charger current is I = (Pcharger × 1000) ÷ D and the total diversified current is (Pdiv × 1000) ÷ D, where the denominator is D = V × PF for single-phase and D = √3 × V × PF for three-phase. By default no diversity is applied (factor 1.0), which is the BS 7671 Section 722 continuous-load position for a single charge point; for multiple points the upstream supply may take diversity per the IET Code of Practice for EV Charging Equipment Installation or the BS 7671 A4:2026 EV maximum-demand table. Always confirm the maximum demand and final circuit design against the current regulations.
Frequently asked questions
What diversity factor should I use for EV chargers?
BS 7671 has historically treated a single charge point as a continuous load with no diversity (factor 1.0), which is the default here. The BS 7671 A4:2026 amendment introduces a normative EV maximum-demand table, roughly 0.6 for a 7 kW single-phase domestic point, rising to 100 % for commercial rapid chargers. For multiple points the figure is engineering judgement informed by the IET Code of Practice and any active load management, so enter the value appropriate to your installation.
Should I enter 230 V or 400 V?
For a single-phase point use 230 V (line-to-neutral); for a three-phase point use 400 V (line-to-line). When you switch the phase selector the calculator updates the default voltage for you, and the √3 factor in the three-phase denominator handles the line-to-phase geometry automatically.
Does the power factor matter for EV chargers?
Modern EV chargers complying with IEC 61851 run close to unity power factor, so the default of 1.0 makes the current match the nameplate kW. If your equipment data quotes a lower power factor, enter it, the supply current rises because more of the apparent kVA is reactive.