Diameter and area are for solid round wire. Stranded wire of the same AWG has about the same copper area but a larger OD (~1.15×).
Resistance is annealed copper at 20 °C. It rises ~0.39%/°C. Multiply by 2 for the out-and-back length of a circuit. See the Voltage Drop calculator.
Chassis: a rule-of-thumb maximum for a single wire in free air over a short run. It is not a code value.
Bundles, enclosures and long runs need derating. Also check voltage drop and the connector or terminal ratings.
NEC 310.16: copper, no more than 3 current-carrying conductors in a raceway or cable, 30 °C ambient.
The column you can use is limited by the lowest temperature rating of the wire and its terminations.
Overcurrent protection for 14/12/10 AWG is capped at 15/20/30 A (NEC 240.4(D)).
Insulated Wire Outside Diameter
SAE J1128 automotive primary wire, cross-linked polyethylene, −51 to 125 °C, 50 V.
TXL = thin wall, GXL = general-purpose (medium) wall, SXL = standard (thick) wall.
OD ranges are from an IEWC spec sheet (J1128 10/2005 / CAT 1E815). The standard treats them as informative,
so check your supplier's data sheet. GXL/SXL at 20 AWG list only a maximum.
UL1007 (300 V, PVC, 1/64" wall) and UL1015 (600 V, PVC, 1/32" wall) are estimates:
stranded conductor + 2× nominal wall. Real OD varies by about ±0.1 mm (±0.004") between manufacturers.
Conductor ≈ is a typical stranded bundle OD (1.15× the solid diameter), useful for sizing crimp barrels and grommets.