AWG to mm Conversion Chart: Wire Diameter, mm², Ampacity & Cable Size Guide
- Vicky
- Jun 17
- 12 min read
Introduction
If you work with electrical cables, solar cables, battery cables, inverter wiring, automotive wiring, or industrial power cables, you will often need an AWG to mm conversion chart. AWG is commonly used in the United States, while many international cable markets use metric sizes such as mm and mm².
The quick answer is this: AWG to mm conversion shows the bare conductor diameter in millimeters, while AWG to mm² conversion shows the conductor cross-sectional area. These two values are related, but they are not the same.
For example, 4 AWG wire has a diameter of about 5.19 mm and a cross-sectional area of about 21.15 mm². In commercial metric cable selection, it is often compared with 25 mm² cable, but 4 AWG and 25 mm² are not exactly identical.
This guide from FRCABLE explains how AWG wire sizes convert to mm and mm², how to compare AWG with metric cable sizes, how ampacity affects cable selection, and how to choose the right cable for solar, battery, inverter, automotive, marine, and power distribution applications.
Quick Answer: What Is AWG to mm Conversion?
AWG to mm conversion is the process of converting American Wire Gauge sizes into metric conductor diameter. It helps buyers, engineers, installers, and distributors compare US wire sizes with international metric cable specifications.
However, for cable selection, you should not only look at diameter in mm. You should also compare cross-sectional area in mm², because mm² is more closely related to current carrying capacity, voltage drop, resistance, and heat generation.
Featured-Snippet Answer
AWG to mm conversion gives the approximate conductor diameter in millimeters. AWG to mm² conversion gives the conductor cross-sectional area. In electrical cable selection, mm² is usually more useful than diameter because it affects ampacity, resistance, and voltage drop.
Why AWG Conversion Matters
AWG conversion is important because different markets use different cable size systems.
The United States commonly uses American Wire Gauge, while many international markets use metric cable sizes such as 1.5 mm², 2.5 mm², 4 mm², 6 mm², 10 mm², 16 mm², 25 mm², 35 mm², 50 mm², and larger sizes.
This creates confusion when comparing:
US electrical wire sizes
IEC cable specifications
UL-listed cables
Solar cable datasheets
Battery cable sizes
Automotive and marine wiring
Power cable procurement documents
Custom cable manufacturing requirements
A clear AWG to metric conversion chart helps prevent ordering mistakes and improves communication between buyers and manufacturers.
AWG to mm and mm² Conversion Chart
The following table shows common AWG sizes, approximate conductor diameter in mm, exact cross-sectional area in mm², and common metric cable equivalents.
AWG Size | Diameter in mm | Area in mm² | Common Metric Equivalent |
18 AWG | 1.024 mm | 0.82 mm² | 1 mm² |
16 AWG | 1.291 mm | 1.31 mm² | 1.5 mm² |
14 AWG | 1.628 mm | 2.08 mm² | 2.5 mm² |
12 AWG | 2.053 mm | 3.31 mm² | 4 mm² |
10 AWG | 2.588 mm | 5.26 mm² | 6 mm² |
8 AWG | 3.264 mm | 8.37 mm² | 10 mm² |
6 AWG | 4.115 mm | 13.30 mm² | 16 mm² |
4 AWG | 5.189 mm | 21.15 mm² | 25 mm² |
2 AWG | 6.544 mm | 33.60 mm² | 35 mm² |
1 AWG | 7.348 mm | 42.40 mm² | 50 mm² |
1/0 AWG | 8.252 mm | 53.50 mm² | 50 / 55 mm² |
2/0 AWG | 9.266 mm | 67.40 mm² | 70 mm² |
3/0 AWG | 10.405 mm | 85.00 mm² | 95 mm² |
4/0 AWG | 11.684 mm | 107.20 mm² | 120 mm² |
This chart is useful for quick reference, but it should not replace engineering judgment. The correct cable size also depends on ampacity, conductor material, insulation rating, installation environment, voltage drop, and applicable electrical standards.
Exact Area vs Common Metric Equivalent
One common mistake is assuming the exact AWG area is the same as the commercial metric equivalent.
For example:
8 AWG is about 8.37 mm², but it is often compared with 10 mm² cable.
4 AWG is about 21.15 mm², but it is often compared with 25 mm² cable.
4/0 AWG is about 107.2 mm², but it is often compared with 120 mm² cable.
The common metric equivalent is usually the nearest standard commercial size, not the exact mathematical match.
Why the Metric Equivalent Is Often Larger
Metric cable sizes are usually standardized by cross-sectional area. Since exact AWG sizes do not always match common metric cable sizes, buyers often choose the nearest larger metric size.
This can provide better current capacity and lower voltage drop, but it must still match the equipment terminals, cable gland, connector, conduit fill, and project specification.
AWG vs mm vs mm²: What Is the Difference?
To use an AWG conversion chart correctly, you need to understand three different measurements: AWG, mm, and mm².
What Is AWG?
AWG stands for American Wire Gauge. It is a wire sizing system widely used in the United States and North American electrical markets.
In the AWG system, a smaller number means a larger conductor. For example, 4 AWG is larger than 8 AWG, and 8 AWG is larger than 12 AWG.
Larger conductors generally have:
Lower resistance
Higher current carrying capacity
Lower voltage drop
Better performance over long cable runs
Greater material cost and weight
What Does mm Mean?
mm means millimeter. In wire sizing, it usually refers to the bare conductor diameter.
For example, 4 AWG has a bare conductor diameter of about 5.19 mm.
This does not include insulation, jacket, shielding, or outer sheath. The actual outside diameter of the finished cable will be larger.
What Does mm² Mean?
mm² means square millimeter. It refers to the cross-sectional area of the conductor.
For electrical cable selection, mm² is often more important than diameter because it directly affects current capacity and resistance.
In metric cable markets, cable sizes are usually named by mm², such as:
2.5 mm² cable
4 mm² cable
6 mm² cable
10 mm² cable
16 mm² cable
25 mm² cable
35 mm² cable
50 mm² cable
70 mm² cable
95 mm² cable
120 mm² cable
This is why AWG to mm² conversion is critical for international cable procurement.
Common AWG to Metric Cable Size Equivalents
When buyers compare AWG and metric cable sizes, they usually need a practical equivalent for purchasing, not only an exact mathematical conversion.
Common AWG to Metric Matching
Here are common commercial comparisons:
AWG Size | Exact Area | Common Metric Size |
14 AWG | 2.08 mm² | 2.5 mm² |
12 AWG | 3.31 mm² | 4 mm² |
10 AWG | 5.26 mm² | 6 mm² |
8 AWG | 8.37 mm² | 10 mm² |
6 AWG | 13.30 mm² | 16 mm² |
4 AWG | 21.15 mm² | 25 mm² |
2 AWG | 33.60 mm² | 35 mm² |
1/0 AWG | 53.50 mm² | 50 / 55 mm² |
2/0 AWG | 67.40 mm² | 70 mm² |
3/0 AWG | 85.00 mm² | 95 mm² |
4/0 AWG | 107.20 mm² | 120 mm² |
These values are useful for cable comparison, but the final choice should be based on the project’s required current, voltage drop limit, insulation system, terminal rating, and compliance requirements.
When You Can Use a Metric Equivalent
A metric equivalent may be suitable when:
The project accepts metric cable sizing
The selected metric size is equal to or larger than the AWG area
The equipment terminals accept the cable
The cable ampacity meets the load requirement
The insulation rating matches the environment
The local electrical standard allows the substitution
When You Should Not Substitute Cable Sizes
Do not substitute AWG with metric cable blindly when:
The equipment manual specifies an exact AWG size
The project is inspected under a specific electrical code
Terminal sizes are limited
UL or NEC requirements must be followed
The cable must match an existing system
Voltage drop or derating has not been checked
For regulated electrical installations, final cable selection should be verified by a qualified electrician or engineer.
AWG Wire Size Chart with Amps
Many users searching for AWG to mm also want an AWG wire size chart with amps. This is understandable because cable size and ampacity are closely connected.
But ampacity is not determined by AWG size alone.
What Affects AWG Wire Ampacity?
Ampacity depends on:
Copper or aluminum conductor
Insulation temperature rating
Ambient temperature
Installation method
Number of current-carrying conductors
Raceway, conduit, tray, or free-air installation
Terminal temperature rating
Local electrical code
Continuous or intermittent load
Voltage drop requirements
A cable with the same AWG size can have different ampacity in different installations.
Copper vs Aluminum Ampacity
Copper has higher conductivity than aluminum. This means copper wire usually carries more current than aluminum wire of the same AWG size.
For example, a 4 AWG copper conductor generally has higher ampacity than a 4 AWG aluminum conductor under comparable conditions.
This is why copper and aluminum cables should not be replaced at the same AWG size without recalculating ampacity and voltage drop.
Temperature Ratings: 60°C, 75°C and 90°C
Ampacity charts often show three temperature columns:
60°C rating
75°C rating
90°C rating
These ratings are related to insulation and termination temperature limits. Even if a cable has 90°C insulation, the final allowable ampacity may be limited by equipment terminals rated for 75°C or 60°C.
This is especially important in building wire, service cable, feeder cable, and power distribution applications.
Why Ampacity Tables Are Not Enough
Ampacity tables provide a starting point, but real installations require additional checks.
For example, a cable may need derating if:
It is installed in a hot environment
Several current-carrying conductors are bundled together
It is placed inside conduit
It runs over a long distance
It is used in a low-voltage DC system
It connects to equipment with lower terminal temperature ratings
Therefore, the best approach is to use AWG to mm conversion for size comparison, then use ampacity and voltage drop calculations for final selection.
AWG to mm for Solar, Battery and Power Cable Applications
Different applications require different cable selection priorities. The right cable for a solar project may not be the same as the right cable for a battery bank or industrial control panel.
AWG to mm for Solar Cable
Solar cables are commonly used in photovoltaic systems, combiner boxes, inverter connections, and battery-based PV systems.
When selecting AWG solar cable size, consider:
PV string current
System voltage
Cable run length
Voltage drop limit
Outdoor UV exposure
Temperature rating
Insulation material
Connector compatibility
Local code requirements
For solar applications, insulation quality is just as important as conductor size. A cable used outdoors should be designed for sunlight resistance, weather exposure, and long-term thermal performance.
AWG to mm for Battery Cable
Battery cable selection is especially sensitive to voltage drop because many battery systems operate at 12V, 24V, or 48V.
A small voltage loss can be significant in low-voltage DC systems.
For battery cable sizing, check:
Continuous current
Surge current
One-way cable distance
Round-trip circuit length
Battery voltage
Acceptable voltage drop
Cable flexibility
Lug and terminal compatibility
In battery systems, a cable may be safe from overheating but still too small because voltage drop is too high.
AWG to mm for Inverter Cable
Inverter cable sizing depends on inverter power, DC voltage, surge current, and cable length.
A 12V inverter draws much more current than a 48V inverter at the same wattage. This means cable sizing should be based on current draw, not only inverter wattage.
For inverter connections, flexible copper cable is often preferred because it is easier to route and terminate.
AWG to mm for Automotive and Marine Cable
Automotive and marine cables often require flexibility, vibration resistance, heat resistance, and corrosion protection.
For marine environments, tinned copper conductors may be preferred because they provide better corrosion resistance than bare copper.
Cable selection should consider:
Engine heat
Moisture exposure
Oil resistance
Abrasion resistance
Flexibility
Battery connection requirements
Crimping and lug quality
AWG to mm for Industrial Power Cable
Industrial power cables may require higher voltage ratings, flame resistance, oil resistance, mechanical durability, and compliance with UL or IEC standards.
For industrial applications, cable buyers should request a full datasheet, not only an AWG size.
How to Choose the Right Cable Size from an AWG Chart
A conversion chart is useful, but it is only the first step. The correct cable size should be selected through a complete technical process.
Step-by-Step Cable Selection Process
Confirm the required current
Identify the continuous current, peak current, and safety margin.
Check the system voltage
Low-voltage systems usually require more attention to voltage drop.
Measure the cable length
Longer cable runs increase resistance and may require a larger conductor.
Choose conductor material
Copper provides better conductivity; aluminum can reduce weight and cost.
Check the AWG to mm² equivalent
Compare the AWG size with the closest metric cable size.
Calculate voltage drop
Especially for solar, battery, inverter, automotive, and marine applications.
Verify ampacity
Check conductor material, insulation rating, temperature column, and installation method.
Confirm terminal compatibility
Make sure lugs, terminals, connectors, and breakers accept the selected cable size.
Review standards and certifications
Check whether the project requires NEC, UL, IEC, TÜV, RoHS, or other compliance.
Request a manufacturer datasheet
Confirm conductor construction, insulation thickness, cable outside diameter, voltage rating, and packaging.
Common Cable Sizing Mistakes
Avoid these common mistakes when using an AWG to mm conversion chart:
Confusing mm with mm²
Assuming metric equivalents are exact matches
Choosing cable based only on diameter
Ignoring ampacity
Ignoring voltage drop
Replacing copper with aluminum without resizing
Using indoor cable outdoors
Ignoring terminal temperature ratings
Forgetting derating factors
Buying cable without checking the datasheet
A good cable selection balances current capacity, voltage drop, flexibility, insulation performance, compliance, and installation conditions.
Buying Guide for AWG and Metric Cable Buyers
For B2B buyers, distributors, contractors, OEMs, and system integrators, AWG conversion is not just a technical topic. It directly affects purchasing accuracy and project reliability.
What to Confirm Before Ordering
Before ordering AWG or metric cable, confirm:
AWG size or metric size
Exact conductor area
Conductor material
Copper, tinned copper, aluminum, or copper-clad aluminum
Solid or stranded construction
Strand count
Insulation material
Cable outside diameter
Voltage rating
Temperature rating
Ampacity reference
Application environment
Required standards
Cable printing or marking
Packaging method
MOQ and lead time
These details help prevent misunderstandings between buyer and supplier.
What Affects Cable Price?
Cable price can vary widely depending on material and construction.
Key price factors include:
Copper or aluminum market price
Conductor size
Strand structure
Insulation material
Voltage rating
Certification requirements
Order quantity
Packaging
Shipping cost
Custom printing
Special flexibility or environmental requirements
The lowest price is not always the best choice. A cable with poor insulation, inaccurate conductor size, or unclear certification can create installation problems and long-term failure risk.
Why Work With FRCABLE
FRCABLE supports buyers who need AWG cable, metric cable equivalents, and custom cable solutions for electrical, solar, battery, inverter, automotive, marine, and power applications.
FRCABLE can help compare AWG and metric cable sizes, review conductor material, provide cable datasheets, and support custom specifications for project-based procurement.
Whether you need standard AWG cable or a metric equivalent such as 10 mm², 16 mm², 25 mm², 35 mm², 70 mm², or 120 mm², professional cable selection can help reduce specification mistakes before production.
FAQ About AWG to mm Conversion
What is AWG to mm conversion?
AWG to mm conversion means converting American Wire Gauge sizes into conductor diameter in millimeters. It helps compare US wire sizes with metric cable specifications.
How do you convert AWG to mm?
You can use an AWG conversion formula or an AWG to mm chart. For practical cable selection, most buyers use a conversion chart because it is faster and reduces calculation errors.
What is AWG to mm² conversion?
AWG to mm² conversion shows the conductor cross-sectional area in square millimeters. This is often more important than diameter when comparing cable current capacity and metric cable sizes.
Is AWG the same as mm²?
No. AWG is a wire gauge system, while mm² is a metric measurement of conductor cross-sectional area. They describe cable size in different ways.
Why does a lower AWG number mean a thicker wire?
In the American Wire Gauge system, smaller AWG numbers represent larger conductors. For example, 4 AWG is thicker than 8 AWG, and 8 AWG is thicker than 12 AWG.
What is 10 AWG in mm²?
10 AWG is approximately 5.26 mm² in exact conductor area and is often compared with 6 mm² cable in commercial metric sizing.
What is 8 AWG in mm²?
8 AWG is approximately 8.37 mm² in exact conductor area and is often compared with 10 mm² cable.
What is 6 AWG in mm²?
6 AWG is approximately 13.3 mm² and is often compared with 16 mm² cable.
What is 4 AWG in mm²?
4 AWG is approximately 21.15 mm² and is often compared with 25 mm² cable.
What is 4/0 AWG in mm²?
4/0 AWG is approximately 107.2 mm² and is often compared with 120 mm² cable in metric sizing.
Which is more important, wire diameter or cross-sectional area?
For electrical performance, cross-sectional area is usually more important because it affects ampacity, resistance, and voltage drop. Diameter is useful for physical size comparison and terminal fit.
Can I replace AWG wire with metric cable?
In some cases, yes, but only if the metric cable meets or exceeds the required ampacity, voltage drop, terminal fit, insulation rating, and applicable electrical code or project specification.
Does ampacity change between copper and aluminum wire?
Yes. Copper has higher conductivity than aluminum, so copper wire usually has higher ampacity than aluminum wire of the same size under comparable conditions.
Where can I buy custom AWG cable?
You can buy custom AWG cable from professional cable manufacturers. FRCABLE provides AWG and metric cable solutions for solar, battery, inverter, automotive, marine, and power cable applications.
Conclusion
An AWG to mm conversion chart is a practical tool for comparing American Wire Gauge sizes with metric cable measurements. It helps users understand conductor diameter, mm² cross-sectional area, and common metric cable equivalents.
The most important point is that mm and mm² are not the same. Diameter in mm shows the physical conductor width, while mm² shows conductor area. For cable selection, mm² is usually more important because it affects ampacity, resistance, voltage drop, and long-term electrical performance.
However, conversion alone is not enough. The correct cable size also depends on conductor material, insulation type, ampacity, terminal rating, voltage drop, installation environment, and applicable standards.
For solar cables, battery cables, inverter cables, automotive cables, marine cables, and industrial power cables, choosing the right AWG or metric cable size can improve safety, efficiency, and reliability.
CTA Closing
Need help choosing the right AWG cable or metric equivalent?
FRCABLE provides professional cable manufacturing and customization support for solar cable, battery cable, inverter cable, automotive cable, marine cable, and power cable applications. Whether you need AWG cable, metric cable, copper conductor, aluminum conductor, or custom cable specifications, our team can help you compare conductor size, ampacity, insulation rating, voltage drop, and application requirements.
Contact FRCABLE today to request a datasheet, quotation, or professional cable selection support for your next project.
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