🔌 Wire Gauge (AWG) Converter
By ToolNimba Engineering Team · Updated 2026-06-19
Use -1, -2, -3 for 0 (1/0), 00 (2/0), 000 (3/0), 0000 (4/0).
Enter a measured conductor diameter to match the closest gauge.
Enter an AWG number, or type a measured diameter to find the closest gauge.
This wire gauge converter turns an American Wire Gauge (AWG) number into the real conductor size: diameter in millimetres and inches, plus the cross-sectional area in square millimetres. You can also work the other way, type a measured diameter and the tool finds the nearest standard gauge. Use it to read a cable spec, match a replacement wire, or sanity-check a part you have in hand.
What is the Wire Gauge Converter?
American Wire Gauge (AWG) is the standard system for sizing solid, round electrical conductors in North America. It is a geometric scale: the gauge number goes up as the wire gets thinner, so 24 AWG is much finer than 12 AWG. The numbering looks backwards at first, but it comes from the manufacturing process, where each gauge step corresponds to one more pass through a drawing die that stretches and narrows the wire.
The whole scale is fixed by one formula. The diameter of a wire in millimetres is 0.127 × 92^((36 − n) ÷ 39), where n is the AWG number. The constants are chosen so that 36 AWG is exactly 0.005 inches (0.127 mm) and 0000 AWG (written 4/0) is 0.46 inches, with 38 even steps between them on a logarithmic curve. A handy consequence: every 6 gauges the diameter roughly halves, and the cross-sectional area, which sets current capacity and resistance, halves about every 3 gauges.
For the very thick conductors below 1 AWG, the scale continues with 0 (one-aught, 1/0), 00 (2/0), 000 (3/0) and 0000 (4/0), which this tool treats as n = 0, -1, -2 and -3. Cross-section is what most electrical work actually cares about, since it governs how much current a wire can carry and how much voltage it drops over a run. That is why cable is often specified in mm² in the rest of the world, and converting between AWG and mm² is one of the most common reasons people reach for a chart like this one.
When to use it
- Reading a North American cable spec given in AWG and converting it to mm or mm² for a project that uses metric parts.
- Finding the nearest AWG for a wire you have measured with a caliper or micrometer.
- Matching a replacement wire to an existing conductor when only the gauge or only the diameter is known.
- Estimating current capacity and resistance, which both depend on the cross-sectional area the converter reports.
How to use the Wire Gauge Converter
- To size a known gauge, type the AWG number (use -1, -2, -3 for 0, 00, 000, 0000).
- Read the diameter in mm and inches and the cross-sectional area in mm² and in².
- To go the other way, enter a measured diameter and pick mm or inch as the unit.
- The tool returns the nearest standard AWG along with its full dimensions.
Formula & method
Worked examples
Convert 12 AWG to diameter and cross-sectional area.
- Exponent = (36 − 12) ÷ 39 = 24 ÷ 39 = 0.615385
- 92^0.615385 = 16.1616
- Diameter = 0.127 × 16.1616 = 2.0525 mm
- In inches = 2.0525 ÷ 25.4 = 0.0808 in
- Area = (π ÷ 4) × 2.0525² = 0.785398 × 4.2129 = 3.3088 mm²
Result: 12 AWG ≈ 2.0525 mm (0.0808 in), area ≈ 3.31 mm²
You measure a conductor at 0.51 mm. Find the nearest AWG.
- n = 36 − 39 × log₉₂(0.51 ÷ 0.127)
- 0.51 ÷ 0.127 = 4.0157
- log₉₂(4.0157) = ln(4.0157) ÷ ln(92) = 1.39021 ÷ 4.52179 = 0.30745
- n = 36 − 39 × 0.30745 = 36 − 11.99 = 24.01
- Round to the nearest whole gauge: 24
Result: Closest standard gauge is 24 AWG (true diameter 0.5106 mm)
AWG to diameter and cross-sectional area (computed from the standard formula)
| AWG | Diameter (mm) | Diameter (in) | Area (mm²) |
|---|---|---|---|
| 0000 (4/0) | 11.6840 | 0.46000 | 107.22 |
| 000 (3/0) | 10.4049 | 0.40964 | 85.03 |
| 00 (2/0) | 9.2658 | 0.36480 | 67.43 |
| 0 (1/0) | 8.2515 | 0.32486 | 53.48 |
| 2 | 6.5437 | 0.25763 | 33.63 |
| 4 | 5.1894 | 0.20431 | 21.15 |
| 6 | 4.1154 | 0.16202 | 13.30 |
| 8 | 3.2636 | 0.12849 | 8.37 |
| 10 | 2.5882 | 0.10190 | 5.26 |
| 12 | 2.0525 | 0.08081 | 3.31 |
| 14 | 1.6277 | 0.06408 | 2.08 |
| 16 | 1.2908 | 0.05082 | 1.31 |
| 18 | 1.0237 | 0.04030 | 0.823 |
| 20 | 0.8118 | 0.03196 | 0.518 |
| 22 | 0.6438 | 0.02535 | 0.326 |
| 24 | 0.5106 | 0.02010 | 0.205 |
| 26 | 0.4049 | 0.01594 | 0.129 |
| 30 | 0.2546 | 0.01003 | 0.0509 |
Quick rules of thumb for the AWG scale
| Change in gauge | Effect on the wire |
|---|---|
| +1 gauge number | Wire gets thinner |
| +3 gauge numbers | Cross-section area roughly halves |
| +6 gauge numbers | Diameter roughly halves |
| +10 gauge numbers | Area drops about tenfold, diameter about one third |
Common mistakes to avoid
- Assuming a bigger number means a bigger wire. AWG runs backwards: a higher gauge number is a thinner wire. 22 AWG is much finer than 10 AWG. Always picture the scale before choosing a wire by its number.
- Confusing diameter with cross-section area. Doubling the diameter quadruples the area. Current capacity tracks area (mm²), not diameter, so comparing wires by diameter alone understates how much extra copper a thicker gauge carries.
- Measuring stranded wire as if it were solid. The AWG formula describes a solid round conductor. A stranded wire of the same gauge has a slightly larger outside diameter because of the gaps between strands, so measure the equivalent copper area, not the bundle.
- Including the insulation in a diameter measurement. The gauge refers to the bare conductor only. Measuring over the insulation gives a larger figure and points you to the wrong gauge, so strip a short length or subtract the insulation thickness.
Glossary
- AWG
- American Wire Gauge, the standard system for sizing solid round electrical conductors, where a higher number means a thinner wire.
- Diameter
- The width of the bare conductor across its circle, here reported in millimetres and inches.
- Cross-sectional area
- The area of the wire end face, (π ÷ 4) × diameter², which governs current capacity and resistance. Often quoted in mm².
- Aught (0-gauge)
- Sizes thicker than 1 AWG, written 0, 00, 000, 0000 (read 1/0 through 4/0), handled as n = 0, -1, -2, -3 in the formula.
- Stranded wire
- A conductor made of several thin strands twisted together, more flexible than a single solid wire of the same gauge.
Frequently asked questions
How do I convert AWG to mm?
Use diameter (mm) = 0.127 × 92^((36 − n) ÷ 39), where n is the AWG number. For example, 12 AWG gives 0.127 × 92^(24 ÷ 39) ≈ 2.05 mm. This converter applies the formula automatically and also shows the result in inches.
Why does a higher AWG number mean a thinner wire?
The number counts how many times the wire was drawn through progressively smaller dies during manufacturing. More draws make a thinner wire, so the gauge number rises as the diameter falls.
How do I convert AWG to mm² (cross-section area)?
First find the diameter from the AWG formula, then compute area = (π ÷ 4) × diameter². For 12 AWG the diameter is about 2.05 mm, so the area is about 3.31 mm². The tool reports the area for you in mm² and in².
What do 0, 00, 000 and 0000 mean?
These are gauges thicker than 1 AWG, read as 1/0, 2/0, 3/0 and 4/0. In the formula they correspond to n = 0, -1, -2 and -3. The largest, 4/0, is 0.46 inches (about 11.68 mm) in diameter.
How much does the size change per gauge?
The scale is geometric. The cross-sectional area roughly halves every 3 gauge numbers and the diameter roughly halves every 6 gauge numbers, so the difference between, say, 10 and 16 AWG is about a fourfold change in area.
Does this tool tell me the current a wire can carry?
Not directly. It gives the physical size (diameter and area), which is the starting point for ampacity, but the safe current also depends on insulation, ambient temperature, bundling and local electrical code, so always check the relevant standard before wiring anything.