What is AWG?
The American Wire Gauge (AWG) system is a standardized method for measuring wire diameter used in North America. Established in 1857, it provides a consistent way to specify wire sizes for electrical conductors.
The Counter-Intuitive AWG Scale
The AWG system works inversely—as the gauge number increases, the wire diameter decreases:
- Smaller AWG number = Larger wire diameter
- Larger AWG number = Smaller wire diameter
- More current capacity with smaller numbers
- System originated from wire drawing process
Common Residential Wire Sizes
Understanding common wire sizes helps with everyday electrical work:
- 18 AWG: Lamp cords, doorbells, thermostats
- 14 AWG: Lighting circuits, standard outlets (15A)
- 12 AWG: Kitchen outlets, bathroom circuits (20A)
AWG Size Progression Rules
The AWG system follows mathematical progression rules that help with calculations.
Quick Reference
Every decrease of 3 gauge numbers approximately doubles the wire's cross-sectional area and current capacity.
Understanding Aught Sizes
Wire sizes larger than 0 AWG are designated with zeros:
- 1/0 (one aught): Larger than 1 AWG
- 2/0 (two aught): Larger than 1/0
- 3/0 (three aught): Larger than 2/0
- 4/0 (four aught): Largest common AWG size
Metric Equivalents
While AWG is standard in North America, many other countries use metric measurements (mm²) for wire size.
Common Misconception
Thicker is not always better. Oversized wire can be difficult to install in tight spaces and may not fit properly in terminals.
Conclusion
Understanding the AWG system is fundamental to electrical work. While the inverse numbering might seem confusing at first, the system provides a standardized, precise method for specifying wire sizes that has served North America well for over 160 years.
Use our Wire Gauge Calculator to determine the correct AWG size for your project.