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AWG Wire Size Calculator

d = 0.127 × 92^((36−n)/39) mm. AWG 10 is 2.588 mm / 5.261 mm².

By Jasper · Updated

Calculator

PASSAWG 10.00 · 2.588 mm5.261 mm² · 1.038e+4 CMIL

ASTM B258: d(mm) = 0.127 × 92^((36−n)/39). 4/0 is n = −3. Enter exactly one quantity.

AWG
10.00
Diameter
2.588 mm (0.1019 in)
Area
5.261 mm²
CMIL
1.038e+4
  • Pass AWG: 10.00 · 2.588 mm · 5.261 mm²
  • Warn Non-integer AWG: Exact 10.00 AWG. Nearest 10; thicker 10; common stock 10.

Formula

ASTM B258 diameter

d=0.127×92(36-n)/39 d(mm) = 0.127 × 92^((36−n)/39)

Variables

Symbol Meaning Unit Typical range Precision Default
n AWG AWG — 4 sig 10 AWG
Amm Area (optional) mm² — 4 sig
d Diameter mm — 4 sig —
A Cross-section mm² — 4 sig —
cmil Circular mils cmil — 4 sig —
nlabel AWG label — — 4 sig —
nnear Nearest integer AWG AWG — 0 dp —
ncommon Common stock AWG AWG — 0 dp —

Worked example

AWG 10

Input Value
n · AWG 10 AWG
Output Value
d · Diameter 2.588 mm
A · Cross-section 5.261 mm²
cmil · Circular mils 1.038e4 cmil

AWG 22

Input Value
n · AWG 22 AWG
Output Value
d · Diameter 0.6438 mm
A · Cross-section 0.3255 mm²

2.5 mm²

Input Value
Amm · Area (optional) 2.5 mm²
Output Value
nlabel · AWG label 13.21
nnear · Nearest integer AWG 13 AWG
ncommon · Common stock AWG 12 AWG

How it works

American Wire Gauge is a logarithmic diameter series, not a round millimetre table. The ASTM B258 closed form lets you convert in both directions, including the 1/0–4/0 names.

Enter one of AWG, mm², diameter or circular mils. Non-integer gauges show the nearest integer, the next thicker integer, and a common stock size.

Pitfalls

  • Mixing AWG number with mm² as if they were the same scale. Enter exactly one quantity.
  • Assuming tables stop at 0 AWG. 1/0 through 4/0 are n = 0 … −3.
  • This page is geometry only. Ampacity needs temperature, insulation and grouping — use the PCB trace tool for copper pours.

FAQ

What is 4/0 in the formula?

n = −3. 3/0 is −2, 2/0 is −1, 1/0 is 0.

How do I go from mm² to AWG?

Enter the area. The page reports the exact (often non-integer) gauge, the nearest integer, and a common stock size.

Is this ampacity?

No. ASTM B258 is diameter and area. Current-carrying capacity depends on the installation.

Does AWG 22 match 0.64 mm?

Yes, about 0.644 mm diameter and 0.326 mm².

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