⚡ Wire Size Calculator
Calculate the correct wire size for your electrical circuit. Combines NEC ampacity requirements with voltage drop calculations for optimal wire selection.
Circuit Requirements
Used for derating calculation (affects ampacity)
Wire Size Selection Guide
Ampacity: The maximum current a wire can safely carry without overheating, determined by NEC Table 310.15(B)(16) and adjusted for temperature and conduit fill.
Voltage Drop: Wire resistance causes voltage loss over distance. NEC recommends limiting voltage drop to 3% for branch circuits.
Both Matter: This calculator finds the optimal wire size that meets BOTH ampacity requirements (safety) and voltage drop limits (efficiency).
Cost vs. Performance: Larger wire costs more but provides better efficiency and future capacity. Consider long-term energy savings.
Disclaimer
This calculator is provided as-is for educational and informational purposes only. While we strive for accuracy, always verify calculations with professional standards and local electrical codes. Use at your own risk. For critical applications, consult a licensed professional electrician.
Round Out Your Wire Planning
Compare project options and specs with help from our trusted partners.
- FormatKit — Developer Data Format Tools
- DiffMaster — Professional Code Comparison Tool
You might also like
Check out another helpful tool from our network:
GridForgeProfessional Printable Paper Templates