Electric Ref: Wire Size & Fill

Type the amps, get the wire size. Pick a conduit, see how many conductors fit. Electric Ref answers the questions electricians ask every day — in three taps, fully offline.

SIZE WIRES CORRECTLY

• Amps to conductor size with temperature correction, conductor bundling adjustment and termination limits applied automatically
• Copper and aluminum, 60/75/90°C insulation
• Small-conductor breaker caps built in
• Every answer shows WHY — the code articles and factors behind it

CONDUIT & BOX FILL

• Max conductors for EMT, RMC, IMC, PVC 40/80, ENT, FMC, LFMC and more
• THHN, XHHW, TW/THW wire types
• Box fill with device, clamp and ground allowances

MORE FIELD TOOLS

• Voltage drop (DC and AC methods, any power factor, conduit material)
• Motor full-load current, conductor and breaker sizing
• Equipment grounding and grounding electrode conductor sizes
• Transformer currents, Ohm's law wheel

REFERENCE CHARTS

• Hole saw and knockout sizes (triple-checked)
• NEMA plug and receptacle configurations
• Motor starter sizes, wire color codes
• Burial depths, conduit support spacing, wire properties

BUILT FOR THE FIELD

• 100% offline — works in basements, new construction, anywhere
• Big glove-friendly controls, screen stays awake
• No account. Your calculations never leave your phone.

ONE-TIME PURCHASE The free version includes the Ohm's law wheel, daily wire sizing and core reference charts. Electric Ref Pro is a single one-time purchase that unlocks every calculator and chart.

No subscription. No ads. No feature removals. Ever.

Values are based on the National Electrical Code®. Reference only — always verify with your locally adopted code edition and AHJ. NEC is a registered trademark of the National Fire Protection Association, which does not endorse this app.