What this calculator does
American Wire Gauge is a standardised numbering system for wire thickness: a lower AWG number means a thicker conductor, and each step of three gauges roughly doubles or halves the cross-sectional area. This wire gauge calculator converts any AWG size into its geometric diameter and cross-sectional area, using the fixed formula that defines the standard.
The AWG scale is a pure geometric progression, so the diameter for any gauge follows a published equation rather than a table that needs updating. This calculator handles the geometry precisely; it does not attempt to give current-carrying capacity (ampacity), since safe current limits depend on insulation type, bundling, ambient temperature and the relevant electrical code, which vary by installation.
The formula
Diameter in millimetres equals 0.127 multiplied by 92 raised to the power of (36 minus the AWG number) divided by 39. This is the defining formula of the AWG standard: gauge 36 is fixed at 0.127 mm, and each whole gauge step scales the diameter by a constant ratio. Cross-sectional area follows from the diameter using the standard circle formula.
| Term | Meaning |
|---|---|
| AWG | American Wire Gauge, the standard sizing scale for round wire; lower numbers are thicker. |
| Diameter | The conductor diameter, calculated in millimetres and converted to inches. |
| Circular mil | A unit of area equal to a circle one thousandth of an inch in diameter, commonly used for wire cross-section in the US. |
The inputs explained
| Field | What to enter |
|---|---|
| Wire gauge (AWG) | The wire gauge number to convert, for example 12 or 14 for common household wiring, or 22 for signal wiring. |
When to use it
Checking a wire size against a spec sheet
Equipment and appliance manuals often specify a required wire gauge; converting that gauge to a diameter or area confirms it matches wire on hand that may be labelled only in millimetres.
Comparing metric and AWG-labelled wire
Wire sold in different countries is labelled in AWG or in millimetres depending on the market, and converting between the two avoids buying the wrong thickness.
Working with automotive or solar 12V wiring
Low-voltage DC systems such as car electrics and solar setups are often specified by AWG; knowing the actual conductor size helps when cross-checking against a manufacturer's wire chart for that application.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How conductor diameter and area change across common wire gauges
A run through commonly used gauges, from heavy-duty to fine signal wire.
| AWG size | Conductor diameter | Cross-sectional area |
|---|---|---|
| AWG 4 | 5.189 mm | 21.151 mm² |
| AWG 8 | 3.264 mm | 8.366 mm² |
| AWG 10 | 2.588 mm | 5.261 mm² |
| AWG 12 | 2.053 mm | 3.309 mm² |
| AWG 14 | 1.628 mm | 2.081 mm² |
| AWG 16 | 1.291 mm | 1.309 mm² |
| AWG 18 | 1.024 mm | 0.8230 mm² |
| AWG 22 | 0.6438 mm | 0.3255 mm² |
Questions
Does a lower AWG number mean a thicker or thinner wire?
Thicker. AWG runs in reverse of what feels intuitive: AWG 4 is a heavy-gauge conductor used for high-current runs, while AWG 22 is thin wire typical of low-current signal or control wiring.
Does this calculator tell me how much current a wire can carry?
No. Safe current-carrying capacity (ampacity) depends on the insulation rating, how the wire is bundled or run in conduit, ambient temperature and the applicable electrical code, not on diameter alone. This calculator gives the geometric size only; check a published ampacity table or a qualified electrician for a real installation.
Why does the "12v" wire gauge question usually come up for automotive or solar wiring?
At 12 volts, even a modest current can create a meaningful voltage drop over a wire run of a few metres, so automotive and solar installers size cable partly around minimising that drop, not just around ampacity. That calculation depends on current, run length and wire resistivity, and is worth checking against a dedicated voltage-drop chart for the wire and application.
Is AWG the same everywhere in the world?
No. AWG is the standard in North America; most of the rest of the world specifies wire by cross-sectional area in square millimetres. This calculator converts between the two so a size given in either system can be checked against the other.
This is a general geometric reference, not a substitute for a qualified electrician or a published ampacity table on any real electrical installation.