🔌 Wire Gauge (AWG) Calculator
Choose an AWG size to see its diameter, cross-section, copper resistance per length and typical current rating.
Diameter
2.05 mm
0.0808 in
Cross-section area
3.31 mm²
Copper resistance
5.08 Ω/km
1.55 Ω/1000 ft
Ampacity — single wire in free air
≈ 41 A
Ampacity — bundled / in conduit
≈ 20 A
Safety: ampacity figures are conservative guidelines, not code. The real safe current depends on the insulation's temperature rating, the ambient temperature, and how many wires are bundled together. For building and mains wiring, always follow your local electrical code (e.g. NEC Table 310.16) and, if in doubt, a qualified electrician.
Diameter = 0.127 × 92^((36 − AWG)/39) mm; resistance uses copper's resistivity (1.68×10⁻⁸ Ω·m at 20°C). A lower AWG number means a thicker wire. 🔒 In your browser.
How the wire gauge (awg) calculator works
American Wire Gauge (AWG) is a logarithmic scale where a lower number means a thicker wire. The diameter follows d = 0.127 × 92^((36 − AWG)/39) mm; from that the tool gives the cross-sectional area and the copper resistance per kilometre and per 1,000 feet (from copper's resistivity). It also lists typical ampacity for a single wire in free air and for bundled/in-conduit wiring.
Ampacity is safety-critical and standard-dependent: the safe current changes with the insulation's temperature rating, the ambient temperature, and how many conductors are bundled. The figures here are conservative guidelines only — for mains and building wiring, follow your local electrical code (e.g. NEC Table 310.16) and consult a qualified electrician.
Frequently asked questions
What gauge wire do I need for a given current?
It depends on the wiring conditions, but as a rough guide for chassis/free-air wiring: about 24 AWG for under ~3 A, 18 AWG for ~10 A, 14 AWG for ~30 A. Bundled or in-conduit wiring must carry less. Always check your local code for mains circuits.
How is AWG diameter calculated?
diameter (mm) = 0.127 × 92^((36 − AWG)/39). 36 AWG is defined as 0.127 mm, and each 6 gauges roughly doubles the diameter (and quadruples the cross-section).
Does a lower AWG number mean a thicker or thinner wire?
Thicker. The scale is inverted: 10 AWG is much thicker (and carries more current) than 24 AWG. Every step down in number is a bigger wire.
What is ampacity?
The maximum current a wire can carry continuously without overheating. It depends heavily on the wire's insulation rating, the ambient temperature and whether the wire is in open air or bundled — which is why a single AWG size has several different ratings.
Why do the two current ratings differ so much?
A single wire in free air sheds heat easily, so it can carry more; the same wire bundled in a conduit runs hotter and must carry less. Use the lower, bundled figure for anything enclosed, and always defer to code for building wiring.