Wire Gauge Calculator

Wire gauge calculations

Wire diameter calculations

The n gauge wire diameter d_n in inches (in) is equal to 0.005in times 92 raised to the power of 36 minus gauge number n, divided by 39:

d_n (in) = 0.005 in × 92^(36-n)/39

The n gauge wire diameter d_n in millimeters (mm) is equal to 0.127mm times 92 raised to the power of 36 minus gauge number n, divided by 39:

d_n (mm) = 0.127 mm × 92^(36-n)/39

Wire cross sectional area calculations

The n gauge wire’s cross sercional area A_n in kilo-circular mils (kcmil) is equal to 1000 times the square wire diameter d in inches (in):

A_n (kcmil) = 1000×d_n² = 0.025 in² × 92^(36-n)/19.5

The n gauge wire’s cross sercional area A_n in square inches (in²) is equal to pi divided by 4 times the square wire diameter d in inches (in):

A_n (in2₎ = (π/4)×d_n² = 0.000019635 in² × 92^(36-n)/19.5

The n gauge wire’s cross sercional area A_n in square millimeters (mm²) is equal to pi divided by 4 times the square wire diameter d in millimeters (mm):

A_n (mm2₎ = (π/4)×d_n² = 0.012668 mm² × 92^(36-n)/19.5

Wire resistance calculations

Resistivity (ρ_(Ω·m))

• copper: 1.72e-8,
• aluminum: 2.82e-8,
• carbon Steel: 1.0e-7,
• electrical Steel: 5.0e-7,
• gold: 2.44e-7,
• nichrome: 1.10e-6,
• nickel: 6.99e-7,
• silver: 1.59e-8

The n gauge wire resistance R in ohms per kilofeet (Ω/kft) is equal to 0.3048×1000000000 times the wire’s resistivity ρ in ohm-meters (Ω·m) divided by 25.4² times the cross sectional area A_n in square inches (in²):

R_n (Ω/kft) = 0.3048 × 10⁹ × ρ_(Ω·m) / (25.4² × A_n (in2₎)

The n gauge wire resistance R in ohms per kilometer (Ω/km) is equal to 1000000000 times the wire’s resistivity ρ in ohm-meters (Ω·m) divided by the cross sectional area A_n in square millimeters (mm²):

R_n (Ω/km) = 10⁹ × ρ_(Ω·m) / A_n (mm2₎

Note:

• Diameter and cross sectional area do not include the insulation.
• Results may change with real wires: different resistivity of material and number of strands in wire
•  20°C or @ 68°F