AWG 37 wire size, resistance and weight calculator
AWG 37 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
- 0.113 097
- Area in circular mils
- 0.019 825 9
- Resistance of that length
- 171.612 ohm
- Resistance per kilometre
- 1716.12 ohm/km
- Resistance per 1000 feet
- 523.073 ohm
- Weight of that length
- 0.009 001 16
- Current at the chosen density
- 0.04 A
- Turns per centimetre, close-wound
- 88.420
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 - (37)) / 39) = 0.113 097
- diameter_in = 0.113 097 / 25.4 = 0.004 452 63
- Cross-sectional area = pi * 0.113 097^2 / 4 = 0.010 045 9
- Area in circular mils = 0.004 452 63^2 * 1000 = 0.019 825 9
- r_per_m_20 = 1.724e-8 / (0.010 045 9 * 1e-6) = 1.716 12
- r_per_m = 1.716 12 * (1 + 0.00393 * (20 - 20)) = 1.716 12
- Resistance of that length = 1.716 12 * 100 = 171.612
- Resistance per kilometre = 1.716 12 * 1000 = 1716.12
- Resistance per 1000 feet = 1.716 12 * 304.8 = 523.073
- Weight of that length = 0.010 045 9 * 1e-6 * 100 * 8960 = 0.009 001 16
- Current at the chosen density = 0.010 045 9 * 4 = 0.040 183 7
- Turns per centimetre, close-wound = 0.113 097 > 0 ? 10 / 0.113 097 : 0 = 88.4199
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 37 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.