Wire Gauge Calculator — AWG Diameter & Resistance
Enter an AWG gauge number to get the wire diameter in millimetres and inches, cross-section area, and DC resistance per metre or per 1000 ft for any conductor material.
Conductor material
m
Conductor diameter calculated from the AWG formula
- 1
Exponent: (36 − n) ÷ 39
(36 − 12) ÷ 39 = 0.6154 - 2
92 raised to the exponent
92^0.6154 = 16.1616AWG is a logarithmic scale with base 92 over 39 steps. - 3
Diameter: 0.127 × result
0.127 × 16.1616 = 2.053
How does this calculator work?
AWG diameter: d = 0.127 × 92^((36 − n) / 39) mm; resistance R = ρ L / A using copper resistivity 1.72 × 10⁻⁸ Ω·m at 20 °C. Enter AWG gauge (use negative for large gauges: −3 = 4/0), wire length, and material to get diameter, area, and DC resistance.
Formula
How this is calculated
The American Wire Gauge (AWG) system is a logarithmic scale: every increase of 6 gauge numbers roughly halves the conductor cross-section, and every increase of 3 roughly halves the diameter. The defining formula is d = 0.127 × 92^((36 − n) / 39) mm, where n is the gauge number. AWG 36 produces the reference diameter of 0.127 mm (0.005 inches); higher numbers (AWG 40) are thinner and lower numbers (AWG 4/0 = −3 in this calculator) are much thicker.
Once the diameter is known, the cross-section area is A = π(d/2)² and the DC resistance per unit length is R/L = ρ/A, where ρ is the material resistivity at 20 °C (copper 1.72 × 10⁻⁸ Ω·m, aluminium 2.82 × 10⁻⁸ Ω·m). The total resistance scales linearly with wire length: R = ρ L / A. These are DC values at 20 °C — resistance rises with temperature (~0.39 % per °C for copper) and AC resistance is slightly higher at high frequencies due to the skin effect.
AWG is the North American standard; metric cables are rated directly by cross-section area in mm². To compare, look up the area in mm² from this calculator and match it to the nearest IEC/metric cable size. Ampacity (current-carrying capacity) depends heavily on insulation rating, ambient temperature, whether the cable is bundled and the installation method — consult NEC Table 310.15 or your local electrical code for rated current values.
Frequently asked questions
In North America, AWG 14 (15 A circuits) and AWG 12 (20 A circuits) are the most common sizes for general household branch circuits. AWG 10 is used for 30 A circuits (dryers, air conditioners) and AWG 8 or 6 for ranges and larger appliances.
Use this calculator to get the diameter in mm, then compute A = π(d/2)². For example, AWG 12 has d ≈ 2.053 mm, giving A ≈ 3.31 mm² — the nearest IEC size is 4 mm². AWG 14 ≈ 2.08 mm² (IEC 2.5 mm²); AWG 10 ≈ 5.26 mm² (IEC 6 mm²).
The AWG system originated from the number of drawing steps needed to produce the wire: a wire drawn 12 times (AWG 12) is thinner than one drawn 10 times (AWG 10). It is counter-intuitive but has been the North American standard since 1857.
Also known as
TG we-Calculate Editorial Team. (2026). Wire Gauge Calculator — AWG Diameter & Resistance [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/wire-gauge-calculator
TG we-Calculate Editorial Team. "Wire Gauge Calculator — AWG Diameter & Resistance." TG we-Calculate. 2026. https://we-calculate.com/calculator/wire-gauge-calculator.
TG we-Calculate Editorial Team, "Wire Gauge Calculator — AWG Diameter & Resistance," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/wire-gauge-calculator
@misc{wecalculate_wire_gauge_calculator, title = {Wire Gauge Calculator — AWG Diameter & Resistance}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/wire-gauge-calculator}}, year = {2026}, note = {TG we-Calculate} }
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