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Wire Gauge Converter

Science

Convert American Wire Gauge (AWG) to wire diameter in millimetres or inches, and cross-sectional area in mm² — for electricians, makers, and cable sizing.

Reviewed by the thecalcu.com team · Last updated July 20, 2026

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What is a Wire Gauge?

A Wire Gauge Converter translates American Wire Gauge (AWG) numbers, the standard sizing system for round electrical wire, into physical dimensions: diameter in millimetres or inches, and cross-sectional area in mm². AWG uses an inverse numbering scale where smaller numbers mean thicker wire, following a precise geometric progression rather than a simple linear scale, which makes mental conversion difficult without a formula or reference chart.

This is especially useful when working across regions or industries that mix sizing conventions, US-sourced components, datasheets, and hobbyist wire spools are almost always labelled in AWG, while Indian and most international electrical standards specify wire in metric mm². Pair it with the Electric Resistance Converter when calculating a wire run's resistance from its gauge.

Why Use a Wire Gauge Converter?

Electrical datasheets, hobbyist electronics kits, and US-manufactured cables specify wire thickness in AWG, but circuit design calculations, ampacity tables, and most non-US electrical codes require the actual diameter or cross-sectional area in metric units. Manually applying the AWG geometric formula, which involves a fractional exponent, isn't something most people can do without a calculator.

Two concrete situations this solves: converting a US datasheet's "22 AWG" wire spec into millimetres to check compatibility with a metric connector or crimp terminal, and calculating the cross-sectional area of a given AWG wire to estimate its current-carrying capacity or resistance per metre.

Who Should Use This Converter?

  • Electricians and electrical engineers cross-referencing US AWG-specified components against metric wire sizing used in Indian and international electrical codes.
  • Makers and hobbyist electronics builders matching AWG hookup wire or spool labels to the physical diameter needed for a connector, crimp, or 3D-printed enclosure.
  • PCB and cable designers calculating cross-sectional area from AWG for current-carrying capacity or voltage-drop estimates.
  • Automotive and marine wiring technicians working with AWG-rated wire in vehicles and boats, where AWG remains the dominant sizing convention regardless of country.
  • Students studying electrical engineering fundamentals, verifying the standard AWG diameter formula against reference tables.

What Insights Does the Wire Gauge Converter Give You?

Converting AWG to Diameter (mm) or Diameter (inches) gives you the physical thickness of the conductor, the number you need for connector sizing, drill bit selection for cable glands, or 3D-printed part clearances. Converting to Cross-Sectional Area (mm²) gives you the value used in current-carrying capacity (ampacity) tables and resistance-per-length calculations, since a wire's ability to carry current scales with its cross-sectional area, not its diameter directly.

Because AWG follows a geometric (not linear) progression, small AWG number changes near the thin end of the scale represent much smaller diameter changes than the same numeric step near the thick end, converting to an actual dimension makes size comparisons accurate rather than relying on gauge-number intuition alone.

How to use this Wire Gauge calculator

  1. Select your starting unit from the From dropdown, American Wire Gauge (AWG), or one of the dimension units if converting the other direction.
  2. Enter the value you want to convert, such as 18 for 18 AWG wire.
  3. Select your target unit from the To dropdown, such as Diameter (mm) or Cross-Sectional Area (mm²).
  4. Read the converted result, which updates instantly.
  5. Use the swap (⇅) button to convert a known diameter or area back into its equivalent AWG number.
  6. Cross-check the result against your component's datasheet or local electrical code before use in a real wiring installation.

Formula & Methodology

All conversions route through wire diameter in millimetres as the canonical unit, using the standard AWG geometric progression formula:

Diameter (mm) = 0.127 × 92^((36 − AWG) ÷ 39)
AWG = 36 − 39 × log(Diameter mm ÷ 0.127) ÷ log(92)

Cross-sectional area is calculated from diameter using the standard circle area formula: Area = (π ÷ 4) × Diameter².

Worked example: Converting 10 AWG to millimetres, Diameter = 0.127 × 92^((36−10)/39) = 0.127 × 92^0.6667 ≈ 2.588 mm. Converting that diameter to cross-sectional area: Area = (π/4) × 2.588² ≈ 5.26 mm², matching the commonly published reference value for 10 AWG wire.

Frequently Asked Questions

American Wire Gauge is a standardised system for specifying the diameter of round electrical wire, where a lower gauge number means a thicker wire and a higher number means a thinner wire. It's the standard used across the US and widely referenced internationally for electrical, electronics, and maker projects.
Diameter (mm) = 0.127 × 92^((36 − AWG) ÷ 39), which reflects the fact that AWG sizes follow a fixed geometric progression, each drop of 3 gauge numbers roughly doubles the wire's cross-sectional area. This converter applies that exact formula, matching the values published in AWG reference tables.
Select American Wire Gauge (AWG) as your From unit and Cross-Sectional Area (mm²) as your To unit, then enter the gauge number, the tool calculates the diameter from the AWG formula and converts it to area using A = π/4 × d². For example, 12 AWG converts to approximately 3.31 mm².
Indian household wiring commonly uses metric mm² sizing (like 1.5 mm², 2.5 mm², 4 mm², 6 mm²) rather than AWG, since India follows the IS (Indian Standard) metric wire sizing convention. This converter is useful for cross-referencing US-sourced components or datasheets specified in AWG against the metric mm² sizes used locally.
AWG is an inverse scale, 10 AWG wire is thicker than 20 AWG wire, which can be counterintuitive at first. This inverse relationship comes from the gauge's historical origin in wire drawing, where the number originally referred to how many drawing passes were needed to reach that thickness, with more passes producing thinner wire.
Wire gauge selection for current-carrying capacity (ampacity) depends on the wire's cross-sectional area, insulation type, and installation conditions, not just the AWG number alone, this converter provides the diameter and area for a given AWG, but always check an ampacity table or electrical code for safe current ratings. As a general reference, 14 AWG (about 2.08 mm²) is commonly rated around 15 amps in US residential wiring, but always defer to local electrical codes.
Wire diameter is a linear measurement across the wire, while cross-sectional area is the actual area of the circular cross-section, which determines how much current the wire can safely carry. Because area scales with the square of diameter, a wire with twice the diameter has four times the cross-sectional area, this converter calculates both so you can use whichever your application requires.
Each step of 1 AWG number changes the diameter by a factor of 92^(1/39), or approximately 1.123, meaning the diameter increases about 12.3% for each decrease of 1 in gauge number. Every 3 AWG steps roughly doubles the cross-sectional area, which is a useful rule of thumb for quick estimates.
No, this converter is scoped to American Wire Gauge (AWG), the dominant global standard for electrical and electronics wire sizing. SWG uses a different, non-formulaic lookup table with no simple geometric relationship, so it isn't included here to avoid publishing approximated values.
USB cables typically use 20–28 AWG conductors depending on cable length and power requirements, with thicker gauges (lower numbers) used for higher-power charging cables to reduce voltage drop. Maker and hobbyist projects commonly use 22 AWG or 24 AWG hookup wire for breadboarding and small circuit connections.
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