Electrical Toolbox

Essential Tools for Electrical Engineers & EV Owners

All calculators run 100% client-side — your data never leaves your browser.

EV Charging

Charging Time Calculator — Enter battery kWh + power kW, get instant 0→80%, 0→90%, 0→100% charging durations. Covers 7 kW to 250 kW.
Charging Power Calculator — Enter V/A/cosφ, get active kW / reactive kVar / apparent kVA. Supports 220 V single-phase and 380 V three-phase.

Power Distribution & Engineering

Three-Phase Power Calculator — Line voltage/current/power factor → active/apparent/reactive power + PF compensation.
Circuit Breaker Size Calculator — NEC 240/430 OCPD sizing with EV charger, motor, and subpanel presets.
Wire Size Calculator — NEC 310.16 AWG/kcmil + voltage drop verification + next-standard OCPD.
Cable Ampacity Lookup — YJV/YJV22/VV lookup covering 5 installation methods per GB 50217.
Transformer Capacity Selection — kVA sizing per GB/T 17468 R10, single/multi-device + motor inrush modes.
Electricity Cost Estimator — Appliance wattage + daily hours + rate → daily/monthly/annual cost + carbon estimate.

Why This Site?

100% Client-Side — All math runs in your browser; your electrical data never leaves your device
Instant Results — No uploads, no queueing, millisecond responses
Engineering Rigor — Formulas based on GB/T, NEC, and IEC standards
EV Owner Friendly — Plain-language explanations + FAQ

Transformer Capacity Selection Calculator — kVA Sizing & GB/T 17468 R10 Standard Ratings

Online transformer capacity selection calculator. Enter power kW, power factor cosφ, efficiency η, and load factor β to quickly estimate required transformer kVA capacity. Recommends GB/T 17468 R10 standard ratings. Supports single-equipment / multi-equipment diversity factor / motor starting current correction. For engineering design, factory distribution, and design institute calculation sheets.

Cable Current-Carrying Capacity Lookup — YJV / YJV22 / VV Online Reference Tool

Online cable ampacity lookup tool supporting YJV / YJLV / VV / VLV / BVR / BLVR and other cable types. Covers 5 installation methods: free-air, conduit, tray, direct burial, and duct. Automatically applies GB 50217 temperature, grouping, and altitude correction factors. For electrical engineering design, on-site construction, and factory maintenance.

Charging Time Calculator — EV & EV Charger Full-Charge Duration Estimator

Free online charging time calculator. Enter battery capacity kWh, charging power kW, and efficiency to estimate 0–100% / 50–80% / 0–80% charging duration. Covers 13 EV charger presets (7/11/22/43kW AC + 30/60/80/100/120/160/240/400/480kW DC).

Circuit Breaker Size Calculator — NEC 240 / 430 OCPD Sizing

Free NEC-aware circuit breaker calculator. Enter amps or kW, get the OCPD per NEC 240.6(A) + 240.4(B) + 125% rule. EV, subpanel, motor presets. No signup.

Electricity Cost Calculator — Household Appliance Daily / Monthly / Annual Cost Estimator

Free online electricity cost estimator. Enter appliance wattage W and daily usage hours (or monthly kWh) plus electricity rate ¥/kWh to calculate daily/monthly/annual costs. Includes presets for LED lights, refrigerators, air conditioners, and water heaters. Assists with household energy savings.

EV Charger Power Calculator — Sizing & Three-Phase Power

Free online EV charger power calculator. Enter voltage V, current A, and power factor cosΦ to calculate active power kW, reactive power kVar, and apparent power kVA. Supports single-phase 220V and three-phase 380V, assisting with charger sizing.

Three-Phase Power Calculator — Active / Apparent / Reactive Power & Power Factor

Online three-phase power and power factor calculator. Enter line voltage V, line current A, and power factor cosφ to calculate active power P(kW), apparent power S(kVA), and reactive power Q(kvar). Supports unit switching (W↔kW, VAr↔kVAr) and recommends reactive power compensation capacitors to correct to 0.95. For factory distribution, motor sizing, transformer capacity verification, and reactive power penalty calculations.

Wire Size Calculator — NEC AWG & kcmil Sizing

Free NEC-aware wire size calculator. Enter amps, voltage, distance & material — get AWG/kcmil with ampacity + 75 °C correction in seconds. No signup.

Essential Tools for Electrical Engineers & EV Owners#

EV Charging#

Power Distribution & Engineering#

Why This Site?#

Essential Tools for Electrical Engineers & EV Owners

EV Charging

Power Distribution & Engineering

Why This Site?