AWG 30 wire size, resistance and weight calculator
AWG 30 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
- 0.254 639
- Area in circular mils
- 0.100 504
- Resistance of that length
- 33.853 ohm
- Resistance per kilometre
- 338.53 ohm/km
- Resistance per 1000 feet
- 103.184 ohm
- Weight of that length
- 0.045 629 7
- Current at the chosen density
- 0.20 A
- Turns per centimetre, close-wound
- 39.271
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 - (30)) / 39) = 0.254 639
- diameter_in = 0.254 639 / 25.4 = 0.010 025 2
- Cross-sectional area = pi * 0.254 639^2 / 4 = 0.050 926
- Area in circular mils = 0.010 025 2^2 * 1000 = 0.100 504
- r_per_m_20 = 1.724e-8 / (0.050 926 * 1e-6) = 0.338 53
- r_per_m = 0.338 53 * (1 + 0.00393 * (20 - 20)) = 0.338 53
- Resistance of that length = 0.338 53 * 100 = 33.853
- Resistance per kilometre = 0.338 53 * 1000 = 338.53
- Resistance per 1000 feet = 0.338 53 * 304.8 = 103.184
- Weight of that length = 0.050 926 * 1e-6 * 100 * 8960 = 0.045 629 7
- Current at the chosen density = 0.050 926 * 4 = 0.203 704
- Turns per centimetre, close-wound = 0.254 639 > 0 ? 10 / 0.254 639 : 0 = 39.2713
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 30 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.