Bendwright Electric Calculator

What it does

Bendwright is an electrical calculator for electricians, apprentices, contractors and inspectors. It works like a hardware calculator: a safety-yellow chassis, real keys and a clear LCD, with each answer labelled so you know what you are reading. Enter lengths in feet, inches and fractions or in metric.

Worked examples

• Offset bend. 4 in offset at 30 degrees -> 8 in between bends (then shrink, multiplier).
• Voltage drop. 3 phase, 208 V, 16 A, 100 ft, 12 AWG copper -> drop 5.47 V, 2.63 %.
• Wire size. 40 A load at 75 C -> 8 AWG copper (50 A).
• Conduit fill. 12 AWG THHN in 3/4 EMT -> 16 conductors at 40 percent.
• Motor current. 2 HP single phase at 230 V -> full-load current 12 A.
• Metric iec drop. IEC mode: 2.5 mm2, 20 A, 30 m at 230 V -> drop 10.8 V (4.7 %).

How it's calculated

Every trade key and the formula behind it, as shown in the app's key guide. A second legend is the shifted function.

Volt ΩVolts / Ohms

Stores the typed voltage, or solves V = I × R, else V = P ÷ (I × PF × √3 for three-phase); shifted stores or solves R = V ÷ I.

Amp kVAAmps / Kilovolt-amps

Stores the typed current, or solves I = V ÷ R, else I = P ÷ (V × PF × √3 for three-phase); shifted gives kVA = V × I × √3 ÷ 1000, or turns a typed kVA into amps.

Watt HPWatts / Horsepower

Stores the typed power, or solves P = V × I × PF (× √3), I² × R or V² ÷ R; shifted stores horsepower, then steps through table full-load current and I = HP × 746 ÷ (V × Eff × PF × √3).

PF EffPower factor / Efficiency

Stores the typed power factor (0.85 or 85), or solves PF = P ÷ (V × I × √3); shifted stores the motor efficiency.

Wire Cu/AlWire size / Copper or aluminum

Stores the typed size (AWG, 0 for 1/0, kcmil; mm² in IEC mode), or picks the smallest size whose ampacity covers the load ÷ derating; press again for the next size up. Shifted toggles metal.

VDrop PhaseVoltage drop / Phase

Voltage drop = 2 (or √3) × K × I × L ÷ cmil, or mV/A/m × I × L in IEC mode, then percent, end voltage, longest run and smallest size for the target; a typed number sets the target percent. Shifted toggles single and three phase.

Len TempLength / Temperature rating

Stores the one-way circuit length (feet, metres in IEC mode). Shifted steps NEC 60, 75, 90 °C columns and IEC mode; a typed factor sets the ambient correction, a typed °C computes it.

Fill BoxConduit fill / Box fill

A typed number sets the conductor count; otherwise gives percent fill against 53, 31 or 40 percent and the most conductors that fit. Shifted: box volume = allowances × volume per conductor.

Bend SaddleOffset bend / Saddle

A typed length sets the offset, a typed angle the bend angle; then distance = offset ÷ sin θ, shrink, multiplier and kick run. Shifted: three-bend saddle shrink 3/16 per inch, marks ±2.5 × depth.

Stub CondStub-up / Conduit

Mark = typed stub height − bender take-up for the stored conduit size. Shifted stores the typed conduit size, or steps EMT, IMC, RMC, PVC 40 and PVC 80.

NEC and NFPA 70 are registered trademarks of the National Fire Protection Association; this app is not affiliated with or endorsed by NFPA. Results are computed from the formulas and tables shown and are provided for reference only. Always verify against the code in force and the authority having jurisdiction, and check local tables in IEC mode. The developer accepts no liability for loss or damage arising from use.