AWG 27 wire size, resistance and weight calculator
AWG 27 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
- 0.360 567
- Area in circular mils
- 0.201 513
- Resistance of that length
- 16.884 ohm
- Resistance per kilometre
- 168.84 ohm/km
- Resistance per 1000 feet
- 51.4625 ohm
- Weight of that length
- 0.091 489
- Current at the chosen density
- 0.41 A
- Turns per centimetre, close-wound
- 27.734
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 - (27)) / 39) = 0.360 567
- diameter_in = 0.360 567 / 25.4 = 0.014 195 5
- Cross-sectional area = pi * 0.360 567^2 / 4 = 0.102 108
- Area in circular mils = 0.014 195 5^2 * 1000 = 0.201 513
- r_per_m_20 = 1.724e-8 / (0.102 108 * 1e-6) = 0.168 84
- r_per_m = 0.168 84 * (1 + 0.00393 * (20 - 20)) = 0.168 84
- Resistance of that length = 0.168 84 * 100 = 16.884
- Resistance per kilometre = 0.168 84 * 1000 = 168.84
- Resistance per 1000 feet = 0.168 84 * 304.8 = 51.4625
- Weight of that length = 0.102 108 * 1e-6 * 100 * 8960 = 0.091 489
- Current at the chosen density = 0.102 108 * 4 = 0.408 433
- Turns per centimetre, close-wound = 0.360 567 > 0 ? 10 / 0.360 567 : 0 = 27.7341
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 27 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.