AWG 15 wire size, resistance and weight calculator
AWG 15 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
- 1.449 53
- Area in circular mils
- 3.256 78
- Resistance of that length
- 1.0447 ohm
- Resistance per kilometre
- 10.447 ohm/km
- Resistance per 1000 feet
- 3.184 24 ohm
- Weight of that length
- 1.478 61
- Current at the chosen density
- 6.60 A
- Turns per centimetre, close-wound
- 6.899
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 - (15)) / 39) = 1.449 53
- diameter_in = 1.449 53 / 25.4 = 0.057 068 2
- Cross-sectional area = pi * 1.449 53^2 / 4 = 1.650 23
- Area in circular mils = 0.057 068 2^2 * 1000 = 3.256 78
- r_per_m_20 = 1.724e-8 / (1.650 23 * 1e-6) = 0.010 447
- r_per_m = 0.010 447 * (1 + 0.00393 * (20 - 20)) = 0.010 447
- Resistance of that length = 0.010 447 * 100 = 1.0447
- Resistance per kilometre = 0.010 447 * 1000 = 10.447
- Resistance per 1000 feet = 0.010 447 * 304.8 = 3.184 24
- Weight of that length = 1.650 23 * 1e-6 * 100 * 8960 = 1.478 61
- Current at the chosen density = 1.650 23 * 4 = 6.600 94
- Turns per centimetre, close-wound = 1.449 53 > 0 ? 10 / 1.449 53 : 0 = 6.898 78
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
Scenarios & local history
Compare a saved scenario
Recent calculations
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 15 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.