AWG 29 wire size, resistance and weight calculator
AWG 29 is defined by the gauge formula, not by a table: the diameter is 0.127 mm times 92 raised to the power (36 - n) / 39. Everything else follows from that and the conductor resistivity.
A rough guide: 3 to 5 A/mm2 for chassis wiring, under 2 for long runs in conduit.
- Diameter
- 0.285 942
- Area in circular mils
- 0.126 733
- Resistance of that length
- 26.8467 ohm
- Resistance per kilometre
- 268.467 ohm/km
- Resistance per 1000 feet
- 81.8287 ohm
- Weight of that length
- 0.057 538
- Current at the chosen density
- 0.26 A
- Turns per centimetre, close-wound
- 34.972
Show the working
- Length of wire = 100
- Conductor = 1.724e-8
- Conductor temperature = 20
- Conductor density = 8960
- Design current density = 4
- Diameter = 0.127 * 92^((36 - (29)) / 39) = 0.285 942
- diameter_in = 0.285 942 / 25.4 = 0.011 257 6
- Cross-sectional area = pi * 0.285 942^2 / 4 = 0.064 216 5
- Area in circular mils = 0.011 257 6^2 * 1000 = 0.126 733
- r_per_m_20 = 1.724e-8 / (0.064 216 5 * 1e-6) = 0.268 467
- r_per_m = 0.268 467 * (1 + 0.00393 * (20 - 20)) = 0.268 467
- Resistance of that length = 0.268 467 * 100 = 26.8467
- Resistance per kilometre = 0.268 467 * 1000 = 268.467
- Resistance per 1000 feet = 0.268 467 * 304.8 = 81.8287
- Weight of that length = 0.064 216 5 * 1e-6 * 100 * 8960 = 0.057 538
- Current at the chosen density = 0.064 216 5 * 4 = 0.256 866
- Turns per centimetre, close-wound = 0.285 942 > 0 ? 10 / 0.285 942 : 0 = 34.9721
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- diameter in mm = 0.127 x 92^((36 - n)/39)
- area = pi d^2 / 4
- resistance = rho x length / area
- temperature correction: R(T) = R(20) x (1 + 0.00393 (T - 20)) for copper
The gauge formula is exact: 36 AWG is 0.127 mm and 0000 AWG is 11.684 mm, with 39 steps between them in a geometric progression of ratio 92^(1/39).
The current figure is a design rule of thumb from current density, not an ampacity rating. Real ampacity depends on insulation temperature rating, bundling, ambient temperature and the wiring code in force.
Aluminium conductors of the same gauge carry about 61% of the current of copper for the same heating.
Frequently asked
What is the diameter of AWG 29 wire?
It follows from the gauge definition: 0.127 mm x 92^((36 - n)/39). The calculator shows the result in millimetres and inches.
Why does the wire gauge number go down as the wire gets thicker?
The number counts drawing operations. Each pass through a die makes the wire thinner and adds one to the gauge, so a high number means a thin wire.