AWG 13 wire size, resistance and weight calculator
AWG 13 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
- 1.827 83
- Area in circular mils
- 5.178 48
- Resistance of that length
- 0.657 018 ohm
- Resistance per kilometre
- 6.570 18 ohm/km
- Resistance per 1000 feet
- 2.002 59 ohm
- Weight of that length
- 2.351 08
- Current at the chosen density
- 10.50 A
- Turns per centimetre, close-wound
- 5.471
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 - (13)) / 39) = 1.827 83
- diameter_in = 1.827 83 / 25.4 = 0.071 961 7
- Cross-sectional area = pi * 1.827 83^2 / 4 = 2.623 98
- Area in circular mils = 0.071 961 7^2 * 1000 = 5.178 48
- r_per_m_20 = 1.724e-8 / (2.623 98 * 1e-6) = 0.006 570 18
- r_per_m = 0.006 570 18 * (1 + 0.00393 * (20 - 20)) = 0.006 570 18
- Resistance of that length = 0.006 570 18 * 100 = 0.657 018
- Resistance per kilometre = 0.006 570 18 * 1000 = 6.570 18
- Resistance per 1000 feet = 0.006 570 18 * 304.8 = 2.002 59
- Weight of that length = 2.623 98 * 1e-6 * 100 * 8960 = 2.351 08
- Current at the chosen density = 2.623 98 * 4 = 10.4959
- Turns per centimetre, close-wound = 1.827 83 > 0 ? 10 / 1.827 83 : 0 = 5.470 98
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 13 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.