AWG 19 wire size, resistance and weight calculator
AWG 19 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
- 0.911 62
- Area in circular mils
- 1.288 13
- Resistance of that length
- 2.641 31 ohm
- Resistance per kilometre
- 26.4131 ohm/km
- Resistance per 1000 feet
- 8.050 72 ohm
- Weight of that length
- 0.584 824
- Current at the chosen density
- 2.61 A
- Turns per centimetre, close-wound
- 10.969
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 - (19)) / 39) = 0.911 62
- diameter_in = 0.911 62 / 25.4 = 0.035 890 5
- Cross-sectional area = pi * 0.911 62^2 / 4 = 0.652 706
- Area in circular mils = 0.035 890 5^2 * 1000 = 1.288 13
- r_per_m_20 = 1.724e-8 / (0.652 706 * 1e-6) = 0.026 413 1
- r_per_m = 0.026 413 1 * (1 + 0.00393 * (20 - 20)) = 0.026 413 1
- Resistance of that length = 0.026 413 1 * 100 = 2.641 31
- Resistance per kilometre = 0.026 413 1 * 1000 = 26.4131
- Resistance per 1000 feet = 0.026 413 1 * 304.8 = 8.050 72
- Weight of that length = 0.652 706 * 1e-6 * 100 * 8960 = 0.584 824
- Current at the chosen density = 0.652 706 * 4 = 2.610 82
- Turns per centimetre, close-wound = 0.911 62 > 0 ? 10 / 0.911 62 : 0 = 10.9695
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 19 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.