## Understanding Wire Size

This page intended for reference purposes and will be updated from time to time.

When trying to understand wire sizes, it’s important to understand the measurement system. Not all the world uses AWG (American Wire Gauge). Most wire available for our hobby today comes in metric, some sizes are close to familiar gauge sizes, some in-between. Most high quality wire today is not sold at an exact AWG size although some is. This leads to some confusion when trying for example to purchase wire that is “about 16 gauge” (or whatever your looking for). Because in America most people are looking for a certain gauge size, we try to list on RadicalRC.com with the nearest approximation of the AWG gauge size. Many vendors claim wire offered is larger than it is in order to exaggerate the perceived value.

To figure the cross sectional area of a stranded wire, measure the diameter of an individual strand. The radius is 1/2 the diameter. If the strands are 0.08mm (typical with the high end wire we offer) then the radius is .04mm. To figure the circular area, we figure that area for a single strand. In the case of the above example, the area* is .00502654832mm^2. Multiply that by the number of strands to get the total area in square mili-meters (mm^2). For example, our Silicone Sub-C wire has 399 of these strands. Multiplying the overly long number above x 399 strands = 2.0055927796 or rounded to 4 digits after the decimal point (proper procedure) we find the area of the 60 strand wire is 2.0056mm^2. When we look down the chart in the Square mm column we see most approximates 14 gauge.

Armed with information and a metric caliper, you figure out if your being “out figured” (hustled) or not.

The following chart is general in nature. I suspect the resistance is calculated based on single strand wire. This may be different for high strand count wire and not the subject of this article.

AWG Diameter(mm) Diameter(in) Square(mm^2) Resistance
(ohm/1000m)
40 0.08 . 0.0050 3420
39 0.09 . 0.0064 2700
38 0.10 0.0040 0.0078 2190
37 0.11 0.0045 0.0095 1810
36 0.13 0.005 0.013 1300
35 0.14 0.0056 0.015 1120
34 0.16 0.0063 0.020 844
33 0.18 0.0071 0.026 676
32 0.20 0.008 0.031 547
30 0.25 0.01 0.049 351
28 0.33 0.013 0.08 232.0
27 0.36 0.014 0.096 178
26 0.41 0.016 0.13 137
25 0.45 0.018 0.16 108
24 0.51 0.02 0.20 87.5
22 0.64 0.025 0.33 51.7
20 0.81 0.032 0.50 34.1
18 1.02 0.04 0.82 21.9
16 1.29 0.051 1.3 13.0
14 1.63 0.064 2.0 8.54
13 1.80 0.072 2.6 6.76
12 2.05 0.081 3.3 5.4
10 2.59 0.10 5.26 3.4
8 3.25 0.13 8.30 2.2
6 4.115 0.17 13.30 1.5
4 5.189 0.20 21.15 0.8
2 6.543 0.26 33.62 0.5
1 7.348 0.29 42.41 0.4
0 8.252 0.33 53.49 0.31
00 (2/0) 9.266 0.37 67.43 0.25
000 (3/0) 10.40 0.41 85.01 0.2
0000 (4/0) 11.684 0.46 107.22 0.16

*Area of a circle = 3.1416 X (Radius X Radius)

## Wire Resistance and Voltage Drop Calculator

Jeff Lucius provides us with his Voltage Drop Calculator. An excellent site to help understand why wire size maters. If you have a 1000kv outrunner and your voltage drop across wires and connectors is .5v then your losing 500 prop RPM. Yikes!