AWG wire gauge calculator
Look up the diameter, area and resistance of an American Wire Gauge size, or find the AWG for a wire diameter.
A clear answer. Here’s how.
AWG is defined by two diameters: 0.005 in at 36 AWG and 0.4600 in at 0000 AWG, with 39 geometric steps between them, so d(n) = 0.127 mm × 92^((36 − n) ÷ 39) with 0000, 000 and 00 counted as −3, −2 and −1. The area is π d² ÷ 4, a circular mil is a circle one thousandth of an inch across, and the resistance per length is ρ ÷ area with ρ = 1 ÷ 58 MS/m for annealed copper (the International Annealed Copper Standard) and 61% of that conductivity for electrical-grade aluminium, corrected to your temperature with a linear coefficient. Looking up a diameter solves the formula for n and rounds to the nearest whole gauge.
How this is checked
5 reference checks passed These 5 cases were run when this page was built, on 20 October 2026, and all reproduce within the stated tolerance. The same cases are part of the automated tests that run on every change to Toolmoz. Engine version 1.
See the checks and where each expected answer comes from
Case 1
- Inputs
- Find gaugeAWG size 10Conductor material copperConductor temperature (°C) 20
- Expected, and what Toolmoz gave
- Diameter (mm) expected 2.5882, Toolmoz 2.5881867280128636Cross-section (mm²) expected 5.2612, Toolmoz 5.261154954510373Resistance (Ω per km) expected 3.2771, Toolmoz 3.2771092011961827
- Where the expected answer comes from
- Published AWG table values for 10 AWG are 2.588 mm, 5.261 mm² and 3.277 Ω/km; these exact figures come from the definition d = 0.127 mm × 92^(26/39) evaluated in 40-digit decimal arithmetic
- Allowed difference
- ±0.0005 absolute
Case 2
- Inputs
- Find gaugeAWG size 0000Conductor material copperConductor temperature (°C) 20
- Expected, and what Toolmoz gave
- Diameter (mm) expected 11.684, Toolmoz 11.684000000000001Diameter (inches) expected 0.46, Toolmoz 0.4600000000000001
- Where the expected answer comes from
- By definition 4/0 AWG is 0.4600 in, which is 11.684 mm
- Allowed difference
- ±1e-9 absolute
Case 3
- Inputs
- Find gaugeAWG size 36Conductor material copperConductor temperature (°C) 20
- Expected, and what Toolmoz gave
- Diameter (mm) expected 0.127, Toolmoz 0.127Diameter (inches) expected 0.005, Toolmoz 0.005
- Where the expected answer comes from
- By definition 36 AWG is 0.005 in, which is 0.127 mm
- Allowed difference
- ±1e-12 absolute
Case 4
- Inputs
- Find gaugeAWG size 14Conductor material aluminiumConductor temperature (°C) 20
- Expected, and what Toolmoz gave
- Cross-section (mm²) expected 2.0809, Toolmoz 2.080907717098377Resistance (Ω per km) expected 13.5828, Toolmoz 13.582801396824607
- Where the expected answer comes from
- Area π/4 × 1.62773² = 2.0809 mm² and aluminium at 61% IACS: 1 ÷ 58 MS/m ÷ 0.61 ÷ 2.0809 mm² = 13.583 Ω/km (40-digit decimal arithmetic)
- Allowed difference
- ±0.001 absolute
Case 5
- Inputs
- Find diameterWire diameter (mm) 1.628Conductor material copperConductor temperature (°C) 20
- Expected, and what Toolmoz gave
- Nearest AWG size expected 14 AWG, Toolmoz 14 AWG
- Where the expected answer comes from
- A diameter of 1.628 mm is the published diameter of 14 AWG
- Allowed difference
- exact
What this shows: the engine reproduces independently worked values for these cases. It does not prove every possible input is right. To test an answer you were given, see how to check a number; to see what is and is not checked across Toolmoz, see the accuracy ledger.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Find
- Dimensions of an AWG size
- AWG size
- 10 AWG
- Conductor material
- Copper (annealed, 100% IACS)
- Conductor temperature (°C)
- 20
Example result
- Diameter (mm)
- 2.5882
- Diameter (inches)
- 0.10190
- Cross-section (mm²)
- 5.2612
- Cross-section (circular mils)
- 10383.0
- Resistance (Ω per km)
- 3.277
- Resistance (Ω per 1000 ft)
- 0.999
AWG sizes follow d = 0.127 mm × 92^((36 − n) ÷ 39), with 0000, 000 and 00 as −3, −2 and −1. Resistance is for solid copper at 20 °C (annealed copper 58 MS/m, aluminium 61% of that, with a linear temperature coefficient). Allowable current (ampacity) depends on insulation, bundling, ambient temperature and local wiring rules, and is not calculated here.