Wire Gauge Reference (AWG)
Look up AWG wire properties: diameter, cross-sectional area, ampacity, and resistance per length. Reverse lookup from target current to recommended gauge.
How to Use
- Enter an AWG number (0-40) to see wire properties.
- Or enter a target current — the tool recommends a minimum gauge for chassis wiring and power transmission.
- Lower AWG = thicker wire. 10AWG > 12AWG > 14AWG.
- Ampacity depends on temperature rise allowance. "Chassis" assumes single wire in open air; "Power" assumes bundled wire with conservative derating.
Details
AWG Formulas
Full AWG Reference (0–40)
| AWG | Diameter (mm) | Area (mm²) | R (mΩ/m) | Chassis (A) | Power (A) |
|---|
History of American Wire Gauge
American Wire Gauge was standardized in 1857 by J.R. Brown & Sharpe of Providence, Rhode Island — originally called the "Brown & Sharpe gauge" and still sometimes labeled "B&S" on older equipment. Brown & Sharpe was the leading US manufacturer of precision machine tools at the time, and their gauge quickly displaced earlier ad-hoc systems (Birmingham Wire Gauge, Washburn & Moen) through sheer adoption in the booming telegraph and electric-lighting industries.
The gauge uses a geometric progression where the ratio of diameters between 0000 (4/0) and 36 is exactly 92:1 — everything else is interpolated logarithmically. This elegant scheme means a simple rule works: each 3-gauge step doubles (or halves) the cross-section. The numbers are "reverse" because the gauge originally counted how many times a wire was drawn through successively smaller dies — more drawings = thinner wire = higher number. Above 0 AWG, the scale continues as 00, 000, 0000, and for massive distribution conductors even 0000000.
Most of the world uses metric cross-sectional area (mm²) instead: IEC 60228 specifies 0.5, 0.75, 1.0, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50 mm². A 2.5 mm² conductor (close to 14 AWG's 2.08 mm²) is Europe's residential standard for 16 A circuits. Engineers working globally often keep AWG↔mm² conversion charts handy — the conversion is approximately (AWG − 3)/3 doublings of area per gauge step.
About This Reference
Enter an AWG number (0-40) to see wire diameter, cross-sectional area, resistance per meter, and ampacity (both chassis and power-transmission grades). Optional length + current inputs compute voltage drop for that run. Reverse mode: enter a target current and the tool recommends the minimum gauge for chassis or power-transmission use.
Ampacity ratings are not fixed — they depend on insulation rating, ambient temperature, bundling, and installation method. The numbers here are reasonable defaults for 75°C insulation in still air at room temperature. For permanent code-compliant installations, consult NEC Table 310.16 (US) or IEC 60364 (Europe). Automotive wiring uses SAE J1128 with 60°C+ engine-bay ambient assumptions. Everything runs client-side; no values leave your browser.
Frequently Asked Questions
How does AWG sizing work?
AWG (American Wire Gauge) uses a geometric sequence: each 3-gauge step halves (or doubles) the cross-sectional area. So 10AWG has 2× the area of 13AWG, and 4× the area of 16AWG. Larger numbers = thinner wire. 0000 (4/0) is very thick; 40AWG is hair-fine.
What's the difference between chassis and power transmission ampacity?
Chassis wiring assumes a short run with good airflow — typical internal equipment wiring. Power transmission assumes long runs, bundled cables, and conservative temperature limits — appropriate for permanent installations. Power-transmission ampacity is typically 30-40% of chassis.
How does wire length affect voltage drop?
V_drop = 2 × I × (R per meter) × length. For a 14AWG wire (8.3 mΩ/m) carrying 15A over 20m round-trip: 2 × 15 × 0.0083 × 20 = 4.98V drop. In a 12V system, that's 41% — unacceptable. Rule of thumb: keep drop below 3% of supply voltage.
Should I use solid or stranded wire?
Solid wire: stiffer, better for permanent installs in conduit, wire nuts, and push-in connectors. Stranded: flexible, better for wiring that moves or gets repeatedly routed. Stranded has slightly higher resistance for the same AWG due to strand air gaps, but the difference is usually negligible.
Does the insulation affect ampacity?
Yes — the insulation's maximum temperature rating limits how much heat the wire can dissipate. THHN (90°C-rated) allows higher current than PVC (60°C) for the same gauge. Industrial derating tables cover this; for home/hobbyist use, default to 75°C ratings unless you know otherwise.
What about AC vs DC ampacity?
For frequencies below ~10kHz, DC and AC ampacity are essentially equal (skin effect is negligible for typical copper wire thicknesses). At RF frequencies, skin effect concentrates current near the wire surface, effectively reducing usable cross-section. Litz wire mitigates this for audio transformers and RF applications.
Common Use Cases
Speaker Wire Sizing
For a 20-foot run of 100W into 8Ω: 16AWG is adequate. Longer runs or higher power? Step up to 14 or 12AWG to keep damping factor high.
Automotive Wiring
A 12V fuel pump drawing 10A over 15 feet → 14AWG wire + 15A fuse. Shorter runs can use 16AWG; high-current starter cables need 2-0AWG or larger.
PCB Current Capacity
Not exactly wire but same idea — PCB trace current limits. 1oz copper @ 10 mil (~30AWG-equivalent cross-section) handles ~1A with 20°C rise.
Home Branch Circuit
US residential: 15A circuits use 14AWG, 20A use 12AWG, 30A dryer use 10AWG, 50A range use 6AWG. Always follow local code + NEC for permanent installs.
3D Printer / CNC Power
Heated-bed wiring pulls 10-15A continuous. 14AWG minimum, 12AWG preferred for safety. Shortening runs keeps voltage drop in check.
Low-Voltage LED Strip
Long LED strip runs sag at the far end due to voltage drop. Inject power at both ends or use heavier gauge to keep brightness uniform end-to-end.
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