Wire Size Calc

Wire Size Calc - professional NEC calculator for electricians. Offline, permit-ready.

NEC wire size calculator for electricians, apprentices, and electrical engineers.

Determine the correct wire gauge (AWG/kcmil) for any circuit using official NEC 2023 ampacity tables and derating factors. Supports continuous and non-continuous loads, copper and aluminum conductors, 6 insulation types, and both conduit and free air installations. No internet required - works 100% offline on the job site.

FEATURES:

• Continuous and non-continuous load sizing (125% factor)
• 5 voltage presets: 120V, 208V, 240V, 277V, 480V
• Single-phase and three-phase support
• Copper and aluminum conductors: 14 AWG through 2000 kcmil
• AWG and mm² (metric) display toggle
• 6 insulation types: THHN, THW, TW, XHHW-2, NM-B, USE-2
• Conduit and free air installation methods
• Temperature correction factor (NEC 310.15(B)(1))
• Conduit fill adjustment factor (NEC 310.15(C)(1))
• Termination rating check (60°C / 75°C per NEC 110.14(C))
• Overcurrent protection sizing (NEC 240.4(D))
• Optional voltage drop check when distance is provided
• PASS/FAIL indicator for quick compliance check

NEC REFERENCES:

• Table 310.16 - Ampacity in conduit/raceway
• Table 310.17 - Ampacity in free air
• Table 310.15(B)(1) - Temperature correction factors
• Table 310.15(C)(1) - Conduit fill adjustment factors
• NEC 110.14(C) - Termination temperature limits
• NEC 240.4(D) - Small conductor overcurrent protection

PRO FEATURES (one-time purchase):

• No ads
• Save calculation history
• Export calculations as PDF reports
• Dark theme support

BUILT FOR THE JOB SITE: This app is designed by electricians, for electricians. Enter your circuit parameters, get the recommended wire size instantly - no complicated menus or unnecessary features. One-hand operation, instant results.

HOW IT WORKS:

1. Enter load current in amps
2. Select load type (continuous or non-continuous)
3. Choose voltage, phase, conductor material, insulation type
4. Set installation method and ambient temperature
5. Get recommended wire size with full derating breakdown

The calculator automatically applies:

• 125% continuous load factor
• Temperature correction for ambient conditions
• Conduit fill adjustment for conductor count
• Termination temperature limit verification
• Standard breaker size selection

PERFECT FOR:

• Licensed electricians
• Electrical apprentices
• Electrical engineers and designers
• Electrical contractors
• NEC code exam preparation
• Journeyman and master electrician exams

OFFLINE & PRIVACY:

• Works 100% offline - no internet needed
• No account required
• No data collection
• Your calculations stay on your device

Simplify your wire sizing on the job site.