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Coil Wire & Drill Bit Sizes

Coil Wire Sizes Conversion

For higher resistance

  • larger diameter wrapping tool (drill bit)
  • thinner wire (higher number AWG)
  • more "wraps" or "coils"
  • or any combination of the above three

For lower resistance

  • smaller diameter wrapping tool (drill bit)
  • thicker wire (lower number AWG)
  • fewer "wraps" or "coils"
  • or any combination of the above three

This chart shows the closest equivalent size between AWG, metric, inches and European wire sizes. (In Europe, wire sizes are expressed in cross sectional area in mm² and also as the number of strands of wires of a diameter expressed in mm. This chart displays the cross sectional area of 0.22mm². With the AWG numbering scheme the numbers are applied to all of the strands. For example 24 AWG could be made of 1 strands of 24 AWG wire or 7 strands of 32 AWG wire.

  Diameter
AWG mm in mm²
10 2.59 0.102 5.26
11 2.30 0.0907 4.17
12 2.05 0.0808 3.31
13 1.83 0.0720 2.62
14 1.63 0.0641 2.08
15 1.45 0.0571 1.65
16 1.29 0.0508 1.31
17 1.15 0.0453 1.04
18 1.02 0.0403 0.823
19 0.912 0.0359 0.653
20 0.812 0.0320 0.518
21 0.723 0.0285 0.410
22 0.644 0.0253 0.326
23 0.573 0.0226 0.258
24 0.511 0.0201 0.205
25 0.455 0.0179 0.162
26 0.405 0.0159 0.129
27 0.361 0.0142 0.102
28 0.321 0.0126 0.0810
29 0.286 0.0113 0.0642
30 0.255 0.0100 0.0509
31 0.227 0.00893 0.0404
32 0.202 0.00795 0.0320
33 0.180 0.00708 0.0254
34 0.160 0.00631 0.0201
35 0.143 0.00562 0.0160
36 0.127 0.00500 0.0127
37 0.113 0.00445 0.0100
38 0.101 0.00397 0.00797
39 0.0897 0.00353 0.00632
40 0.0799 0.00314 0.00501

Frequently Asked Questions

What are the threads on 510 and eGo batteries?
The 510 has a right hand thread, M7 x 0.5 mm
The eGo:has a right hand thread, M12 x 0.5 mm

What’s the difference between a regular coil and a micro coil?
A regular coil is usually wrapped around a 2.0 or 2.5mm silica wick using small wire (32 AWG). The coils themselves are usually spaced apart and not touching each other. If you were to take apart a pre-made coil, like a Kanger for example, this is what you would find. A micro coil is wrapped so that the coils touch each other -- that is one of the features. These are usually heated and pressed together to make the coils as close as possible to each other. The advantage of a micro coil is that they provide more concentrated metal contact with the eLiquid with the main heat (glow) distribution from the center outward. Micro coils are more often associated with cotton wicks which, arguably, improves flavor.

Which brand is better: Kanthal or Nichrome?
Quite frankly it does not matter which you use. The brand of wire is a personal choice. Once you choose, you will not likely switch brands. With each brand there are choices you can make, such as round wire or flat. Flat wire has its followers claiming that more metal gets into contact with the eLiquid and further improves flavor. You cannot go wrong with either brand, though. Once aspect you need to be aware of: each brand have different grades of wire. You need to make sure you get a wire that is suited to building vaping coils.

  • Nichrome 60
    – Melting Temperature: 1350°C (2462°F)
    – Maximum Operating Temperature: 1150°C (2100°F)
    – Density: 0.2979 lbs/cubic in.
    – Specific heat capacity @ 68°F: 0.11 Btu/lb°F
    – Thermal Expansion: 14 x 10 to the -6 per °C
    – 60% nickel, 16% chromium, 24% iron
  • Kanthal A1
    – Melting Temperature: 1500°C (2732°F)
    – Maximum Operating Temperature: 1400°C (2550°F)
    – Density: 0.256 lbs/cubic in.
    – Specific heat capacity @ 68°F: 0.11 Btu/lb°F
    – chromium: 20.5% to 23.5%, iron: 70 to 75%
  • Kanthal D
    – Melting Temperature: 1500°C (2732°F)
    – Maximum Operating Temperature: 1300°C (2370°F)
    – Density: 0.262 lbs/cubic in.
    – Specific heat capacity @ 68°F: 0.11 Btu/lb°F
    – chromium: 20.5% to 23.5%, iron: 70 to 75%

Which gauge wire, for what resistance?

  • 34 gauge = 3.0-2.5 ohms
  • 32 gauge = 2.4-2.0 ohms
  • 30 gauge = 1.9-1.1 ohms
  • 28 gauge = 1.1-.8 ohms
  • 26 gauge = 0.7 ohms and below
... note most regulated mods cannot use coils below 1.4 to 1.5 ohms. Check the mod before you build your masterpiece coil.

What is a "twisted" wire coil? Twisted wire coil is a way to use thinner wire that is less expensive using two or more strands "twisted" together to form a thicker wire. As noted above, you can use 7 strands of 32 AWG wire "twisted" together to get the equivalent of 24 AWG wire. The other aspect of "twisting" wire together to build one coil is that you are also achieving the same result, in a manner of speaking, as having a dual coil setup.
Rules of thumb

  • When the diameter of a wire is doubled, the AWG will decrease by 6. (ie. 26 AWG is about twice the diameter of 32 AWG)
  • When the cross-sectional area of a wire is doubled, the AWG will decrease by 3. (ie. Two 32 AWG wires have about the same cross-sectional area as a single 29 AWG wire)

Drill Bit Sizes Conversion

This chart shows the closest equivalent size between Fractional Inches, Decimal Inches, Millimeters, and standard machinist’s size number. Drill bits, also called twist drills are available with straight or tapered shanks though the most common drill bits will have straight shanks. Drill bits are not the only wrapping medium, you can also use toothpicks, jewelry push pins, micro screwdriver shafts, or a stepped mandrel.

Frac. in Dec. in mm size
  .0135 .3429 #80
  .0145 .3683 #79
1/64 .015625 .3969  
  .016 .4064 #78
  .018 .4572 #77
  .0197 .5  
  .02 .508 #76
  .021 .5334 #75
  .0225 .5715 #74
  .024 .6096 #73
  .025 .635 #72
  .026 .6604 #71
  .028 .7112 #70
  .0292 .74168 #69
  .0295 .75  
  .031 .7874 #68
1/32 .03125 .7938  
  .032 .8128 #67
  .033 .8382 #66
  .0335 .85  
  .035 .889 #65
  .036 .9144 #64
  .037 .9398 #63
  .0374 .95  
  .038 .9652 #62
  .039 .9906 #61
  .0394 1  
  .04 1.016 #60
  .041 1.0414 #59
  .042 1.0668 #58
  .043 1.0922 #57
  .0433 1.1  
  .0465 1.1811 #56
3/64 .046875 1.1906  
  .0492 1.25  
  .0512 1.3  
  .052 1.3208 #55
  .055 1.397 #54
  .0571 1.45  
  .0591 1.5  
  .0595 1.5113 #53
1/16 .0625 1.5875  
  .063 1.6  
  .0635 1.6129 #52
  .067 1.7018 #51
  .0689 1.75  
  .07 1.778 #50
  .073 1.8542 #49
  .076 1.9304 #48
5/64 .078125 1.9844  
  .0785 1.9939 #47
  .0787 2  
  .0807 2.05  
  .081 2.0574 #46
  .082 2.0828 #45
  .086 2.1844 #44
  .089 2.2606 #43
  .0935 2.3749 #42
3/32 .09375 2.3813  
  .096 2.4384 #41
  .098 2.4892 #40
  .0984 2.5  
  .0995 2.5273 #39
  .1015 2.5781 #38
  .104 2.6416 #37
  .1065 2.7051 #36
7/64 .109375 2.7781  
  .11 2.794 #35
  .111 2.8194 #34
  .113 2.8702 #33
  .1142 2.9  
  .116 2.9464 #32
  .1181 3  
  .12 3.048 #31
1/8 .125 3.175  
  .1285 3.2639 #30
  .1299 3.3  
  .136 3.4544 #29
  .1378 3.5  
  .1405 3.5687 #28
9/64 .140625 3.5719  
  .1417 3.6  
  .144 3.6576 #27
  .1457 3.7  
  .147 3.7338 #26
  .1495 3.7973 #25
  .152 3.8608 #24
  .154 3.9116 #23
5/32 .15625 3.9688  
  .157 3.9878 #22

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