Enter the American Wire Gauge (AWG) size and select the output units to determine the decimal wire diameter in inches or millimeters.
Quick Overview: American Wire Gauge (AWG) is a logarithmic sizing system used for round conductors.
A smaller AWG number means a thicker wire, while a larger AWG number means a thinner wire. This converter calculates the wire diameter directly from the standard AWG relationship and reports the result in decimal inches or millimeters.
- AWG 8 = 0.1285 in ≈ 3.26 mm
- AWG 10 = 0.1019 in ≈ 2.59 mm
- AWG 12 = 0.0808 in ≈ 2.05 mm
- AWG 14 = 0.0641 in ≈ 1.63 mm
- AWG 18 = 0.0403 in ≈ 1.02 mm
The calculator above applies the standard AWG formula automatically for any value you enter from 0 to 40.
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Gauge to Decimal Formula (AWG)
The following formula is used to calculate the decimal wire diameter in inches from an American Wire Gauge value.
d(in) = 0.005 * 92^((36 - AWG) / 39)
To convert the result into millimeters, use the following relationship:
d(mm) = d(in) * 25.4
Variables:
- d(in) is the decimal diameter in inches
- d(mm) is the decimal diameter in millimeters
- AWG is the American Wire Gauge size
To calculate the decimal diameter, enter the AWG size into the formula to find the diameter in inches, then multiply by 25.4 if you need the value in millimeters.
What is Gauge to Decimal Conversion?
Gauge to decimal conversion is the process of translating an American Wire Gauge number into an actual wire diameter. Since AWG is a logarithmic system rather than a direct measurement, the gauge number itself does not tell you the wire size in inches or millimeters unless it is converted. This makes the conversion useful for wiring design, product specifications, engineering drawings, and comparing wire sizes across inch and metric systems.
How to Calculate Gauge to Decimal?
The following steps outline how to calculate the decimal wire diameter from an AWG size.
- First, determine the American Wire Gauge size (AWG).
- Next, calculate the diameter in inches using the formula d(in) = 0.005 × 92^((36 − AWG) / 39).
- Then, if needed, convert the inch value into millimeters using d(mm) = d(in) × 25.4.
- Finally, compare your result with the calculator above to verify the answer.
Gauge to Decimal Conversion Table (AWG)
The table below lists several common AWG sizes and their approximate decimal diameters in inches and millimeters.
| Gauge (AWG) | Diameter (inches) | Diameter (mm) |
|---|---|---|
| 8 | 0.1285 | 3.26 |
| 10 | 0.1019 | 2.59 |
| 12 | 0.0808 | 2.05 |
| 14 | 0.0641 | 1.63 |
| 16 | 0.0508 | 1.29 |
| 18 | 0.0403 | 1.02 |
| 20 | 0.0320 | 0.81 |
In practice, manufacturers may list wire size as either AWG or as a direct decimal diameter. Converting between the two makes it easier to compare dimensions, match specifications, and work between imperial and metric measurement systems.
Example Problem:
Use the following variables as an example problem to test your knowledge.
Gauge (AWG) = 10
Diameter (inches) = 0.005 × 92^((36 − 10) / 39) = 0.1019 in
Diameter (millimeters) = 0.1019 × 25.4 = 2.59 mm