Wire & Cable calculator
Wire Gauge Converter
Wire gauge converter for comparing conductor specifications with AWG, metric area, and diameter values. The page keeps AWG/metric conversions separate from NEC ampacity, temperature correction, installation derating, and adopted-code checks.
Updated August 4, 2026
12 AWG = 3.31 mm². A 1.5 mm² metric reference sits near 15 AWG by area, so confirm the available AWG size, ampacity, terminals, and installation conditions separately.
AWG to mm²: Area = 0.012668 × 92^((36-AWG)/39)
Enter AWG or mm² for geometric conversion before separate ampacity and code checks
Example Calculations
More examples. Open to review 1 additional calculation example.
How to Use
Wire Gauge Quick Conversion Formula & Tables
AWG to mm²: Area (mm²) = 0.012668 × 92^((36-AWG)/39) | AWG to Diameter: d (mm) = 0.127 × 92^((36-AWG)/39) | Key Rule: Every 3 AWG = 2× area change (e.g., 10 AWG is 2× area of 13 AWG)
What Wire Gauge Conversions Really Impact in Electrical Work
| Wire Sizing System | Measurement Basis | Common Sizes | Geographic Usage |
|---|---|---|---|
| AWG (American Wire Gauge) | Logarithmic scale, smaller # = larger wire | 14, 12, 10, 8, 6, 4, 2, 1/0, 2/0 | North America, some Asia |
| Metric (mm²) | Cross-sectional area, larger # = larger wire | 1.5, 2.5, 4, 6, 10, 16, 25, 35 | Metric equipment documentation |
| SWG (Standard Wire Gauge) | British Imperial system | 16, 14, 12, 10, 8, 6, 4, 2 | UK, former British territories |
| metric conductor data | International standard, mm² based | 0.75, 1, 1.5, 2.5, 4, 6, 10 | International equipment |
AWG Zero Notation System (Critical for Large Conductors)
| Standard Notation | Alternative Names | AWG Formula Value | Area (mm²) |
|---|---|---|---|
| 1/0 AWG | "one aught" or "0 AWG" | AWG = 0 | 53.5 mm² |
| 2/0 AWG | "two aught" or "00 AWG" | AWG = -1 | 67.4 mm² |
| 3/0 AWG | "three aught" or "000 AWG" | AWG = -2 | 85.0 mm² |
| 4/0 AWG | "four aught" or "0000 AWG" | AWG = -3 | 107.2 mm² |
Important: After 1 AWG, the next larger size is 1/0 (not 0 AWG), then 2/0, 3/0, and 4/0. The notation "4/0" and "0000" refer to the same wire size. In the AWG formula Area = 0.012668 × 92^((36-AWG)/39), use negative numbers: 1/0 = 0, 2/0 = -1, 3/0 = -2, 4/0 = -3. Never confuse "0 AWG" (which is 1/0) with zero in the formula.
Complete AWG to Metric Conversion Table (NEC-informed Standards)
| AWG Size | Area (mm²) | Diameter (mm) | Typical Applications |
|---|---|---|---|
| 4/0 (0000) | 107.2 mm² | 11.68 mm | Service entrances, large feeders |
| 3/0 (000) | 85.0 mm² | 10.40 mm | Service entrances, main feeders |
| 2/0 (00) | 67.4 mm² | 9.27 mm | Subpanels, large appliances |
| 1/0 (0) | 53.5 mm² | 8.25 mm | Subpanels, heavy appliances |
| 2 AWG | 33.6 mm² | 6.54 mm | Large appliances, subpanels |
| 4 AWG | 21.2 mm² | 5.19 mm | Central A/C, electric ranges |
| 6 AWG | 13.3 mm² | 4.11 mm | A/C units, water heaters |
| 8 AWG | 8.37 mm² | 3.26 mm | Appliances, small motors |
| 10 AWG | 5.26 mm² | 2.59 mm | Dryers, A/C disconnect |
| 12 AWG | 3.31 mm² | 2.05 mm | General circuits, 20A branch |
| 14 AWG | 2.08 mm² | 1.63 mm | Lighting, 15A receptacles |
| 16 AWG | 1.31 mm² | 1.29 mm | Control, lighting, doorbells |
| 18 AWG | 0.82 mm² | 1.02 mm | Low voltage, thermostats |
Metric (metric conductor data) to AWG Equivalent Conversion
| Metric Size (mm²) | Closest AWG | AWG Actual Area | Conversion Rule |
|---|---|---|---|
| 0.75 mm² | 18 AWG | 0.82 mm² | Use 18 AWG (10% larger) |
| 1.0 mm² | 17 AWG | 1.04 mm² | Use 16 AWG for NEC (1.31 mm²) |
| 1.5 mm² | 15 AWG | 1.65 mm² | Use 14 AWG for NEC (2.08 mm²) |
| 2.5 mm² | 13 AWG | 2.62 mm² | Use 12 AWG for NEC (3.31 mm²) |
| 4 mm² | 11 AWG | 4.17 mm² | Use 10 AWG for NEC (5.26 mm²) |
| 6 mm² | 9 AWG | 6.63 mm² | Use 8 AWG for NEC (8.37 mm²) |
| 10 mm² | 7 AWG | 10.5 mm² | Use 6 AWG for NEC (13.3 mm²) |
| 16 mm² | 5 AWG | 16.8 mm² | Use 4 AWG for NEC (21.2 mm²) |
Critical Conversion Considerations (Physical vs Electrical)
| Consideration | Issue | Solution |
|---|---|---|
| Electrical Capacity | 1.5 mm² → 16 AWG (1.31 mm²) is 14% undersized for current | Always round UP: use 14 AWG (2.08 mm²) for NEC compliance |
| Terminal Fit | 14 AWG (2.08 mm²) may be too large for 1.5 mm² terminal blocks | Use ferrules or verify terminal accepts 14 AWG. Consider 16 AWG + derating if tight fit required. |
| Stranded vs Solid | Stranded wire has ~5-8% less copper area than solid (air gaps) | For ampacity, use conductor CSA. For terminal fit, verify actual OD with manufacturer specs. |
| Tolerance | Manufacturing tolerance ±5% affects actual area | For critical applications, verify with manufacturer data. NEC uses nominal values. |
| Insulation OD | 12 AWG THHN (2.78mm OD) vs 2.5 mm² PVC (3.2mm OD) | For conduit fill, use actual cable OD from NEC Chapter 9 or manufacturer tables, not bare conductor diameter. |
Conductor Material Properties and Performance Characteristics
| Conductor Material | Conductivity (% IACS) | Temperature Coefficient | Common Applications |
|---|---|---|---|
| Copper (99.95% Pure) | 100% IACS (58.0 MS/m) | 0.393%/°C (20°C ref) | Standard building wire, precision applications |
| Aluminum (99.5% Pure) | 61% IACS (35.4 MS/m) | 0.403%/°C (20°C ref) | Service entrances, large feeders, overhead lines |
| Silver (99.9% Pure) | 106% IACS (61.4 MS/m) | 0.380%/°C (20°C ref) | High-frequency, aerospace, specialized RF |
| Copper-Clad Aluminum (CCA) | 65-68% IACS (avg 66%) | 0.395%/°C (composite) | Telecommunications, data cables (not power) |
| Copper-Clad Steel (CCS) | 20-40% IACS (mechanical) | 0.350%/°C (composite) | Overhead transmission, grounding, guy wire |
NEC Article 310.15 Temperature and Installation Correction Factors
| Installation Condition | Derating Factor | Effective Ampacity Impact | Wire Size Adjustment |
|---|---|---|---|
| Ambient > 30°C (86°F) | 0.82 (40°C), 0.71 (45°C), 0.58 (50°C) per Table 310.15(B)(2)(a) | 20A → 16.4A (40°C ambient) | Use next larger size or derate load |
| More than 3 Current-Carrying | 0.80 (4-6), 0.70 (7-9), 0.50 (10-20) per Table 310.15(B)(3)(a) | 20A → 16A (4-6 conductors) | Increase wire size or separate circuits |
| Continuous Load (3+ hours) | 0.80 (125% sizing rule per 210.19(A)(1)) | 16A continuous → 20A circuit min | Size for 125% of continuous load |
| Aluminum vs Copper | ~0.78 (aluminum conductivity) | Use 2 AWG sizes larger typically | 12 AWG Cu → 10 AWG Al equivalent |
Conductor Selection Matrix
| Application Type | Recommended Material | Sizing Considerations | Selection Notes |
|---|---|---|---|
| Branch Circuits (15-50A) | Copper THWN/THHN | Standard NEC Table 310.15(B)(16) | Smart home integration, EV readiness |
| Service Entrances (100A+) | Aluminum XHHW or Copper | Cost vs performance analysis | Solar integration, energy storage systems |
| Motor Circuits | Copper (VFD considerations) | 125% motor FLA, harmonic analysis | VFD cable specifications, shielding |
| Data Centers | Copper, tight bend radius | Harmonic derating, neutral sizing | AI loads, liquid cooling systems |
| Solar/Battery Systems | Copper, UV-rated XHHW-2 | 125% continuous, temperature rise | Rapid shutdown, smart inverters |
Critical Conversion Rule: Always round UP to the next larger AWG size when converting from metric to AWG for NEC installations to maintain electrical capacity. Example: 1.5 mm² = 15.5 AWG theoretical → use 14 AWG (2.08 mm²), not 16 AWG (1.31 mm²). However, if using imported equipment with metric terminal blocks, verify physical fit. For metric-to-metric work, use exact metric conductor data standard sizes: 0.75, 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300 mm².
Project coordination: Modern conductor selection can involve EV charging, renewable energy equipment, VFD loads, and building controls. Keep those project requirements separate from the basic AWG-to-metric conversion result, then verify ampacity and installation conditions against the adopted code path.
For comprehensive wire sizing, use NEC Wire Size Calculator for ampacity-based sizing, Voltage Drop Calculator for circuit length analysis, and Conduit Fill Calculator for multi-wire installations. Always verify conversions against local codes.
Common Applications
More applications. Open to review 9 additional use cases.
Frequently Asked Questions
How do I perform accurate wire gauge conversions with NEC ampacity checks kept separate?
Wire gauge conversion requires separating physical dimensions from ampacity. AWG uses logarithmic scaling: Area = 0.012668 × 92^((36-AWG)/39) mm². When a metric conductor is compared with an AWG size for a U.S. installation, choose the final conductor only after checking the actual ampacity, insulation, terminal temperature, and adopted NEC path. For equipment documentation, keep the exact metric conductor area beside the converted AWG value.
What are the critical differences between conductor materials and how do they affect wire sizing?
Conductor material affects resistance, termination requirements, and ampacity review. Copper and aluminum should not be treated as interchangeable just because their converted areas look similar. Verify conductor material, insulation, terminal compatibility, and equipment instructions before using the converted gauge in a design or installation note.
How do NEC 310.15 derating factors affect conductor selection and sizing?
NEC 310.15 ampacity correction and adjustment factors can change the conductor size selected after a gauge conversion. Treat the converted AWG or metric area as a reference value first, then review ambient temperature, current-carrying conductor count, terminal rating, insulation type, continuous-load treatment, and local amendments before final selection.
What are the critical considerations for international wire gauge conversions in modern electrical systems?
International conversions require analysis beyond simple mathematical relationships. Key considerations: 1) Standard compliance: Use AWG for NEC installations, metric conductor data metric sizes for international equipment. 2) Terminal compatibility: Verify physical fit with manufacturer specifications - 14 AWG may not fit 1.5 mm² terminal blocks. 3) Ampacity differences: Different countries use varying temperature ratings and installation methods affecting current capacity. 4) Conductor materials: non-U.S. installations often use aluminum where North American codes prefer copper. 5) Installation methods: manufacturer and NEC have different derating factors for conduit, cable tray, and burial installations. 6) Harmonic considerations: VFD and electronic load installations require neutral sizing analysis per local codes. Always verify final selections with local authorities having jurisdiction (AHJ) and applicable electrical codes.
How do modern electrical systems affect conductor selection and wire gauge requirements?
Modern electrical systems can add project-specific conductor requirements. EV charging, solar and battery equipment, VFD motor loads, and controls may require attention to continuous-load treatment, temperature, voltage drop, shielding, equipment instructions, and future load planning. Keep those checks separate from the simple gauge conversion.
What are the best practices for conductor material selection and thermal review?
Conductor selection should document material, insulation, terminal compatibility, ambient temperature, current-carrying conductor count, voltage drop, conduit fill, equipment instructions, and any required local review. Use the converter to keep the physical size reference clear, then complete the ampacity and installation checks in the dedicated sizing workflow.
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