Wire Gauge Comparison Calculator
Compare AWG and metric wire sizes by conductive area, equivalent diameter, circular mils, resistance per length, conductor mass, voltage drop, power loss, and current density. It is a comparison tool, not an AWG converter, wire-size recommender, ampacity calculator, or electrical-code sizing result.
Engineering tool
Wire Gauge Comparison Calculator
Compare AWG, metric area, circular mils, resistance per unit length, conductor mass, and optional operating voltage-drop metrics for candidate wire sizes.
Wire candidates
Compare 2 to 4 candidate sizes. Wire A is compared against Wire B as the baseline.
Wire A
areaWire B
areaResult console
- Area Ratio
- 2Wire A/Wire B
- Area Difference
- 100% relative to Wire B
- Resistance Ratio
- 0.5Wire A/Wire B
- Resistance Difference
- -50% relative to Wire B
- Mass Ratio
- 2Wire A/Wire B
- Mass Difference
- 100% relative to Wire B
Comparison Table
| Metric | Wire A | Wire B |
|---|---|---|
| Input Size | 2.5 mm² | 1.25 mm² |
| AWG / Nearest AWG | Nearest AWG 13 (not exact) | Nearest AWG 16 (not exact) |
| Area | 2.5 mm² | 1.25 mm² |
| Equivalent Diameter | 1.784124 mm | 1.261566 mm |
| Circular Mils | 4,933.8131 cmil | 2,466.9066 cmil |
| Resistance / Meter | 0.006896 Ω/m | 0.013792 Ω/m |
| Resistance / Kilometer | 6.896 Ω/km | 13.792 Ω/km |
| Resistance / 1000 ft | 2.101901 Ω/1000 ft | 4.203802 Ω/1000 ft |
| Mass / Meter | 22.4 g/m | 11.2 g/m |
| Mass / Kilometer | 22.4 kg/km | 11.2 kg/km |
| Mass / 1000 ft | 15.052105 lbm/1000 ft | 7.526053 lbm/1000 ft |
| Conductor Resistance | 0.06896 Ω | 0.13792 Ω |
| Voltage Drop | 0.6896 V | 1.3792 V |
| Power Loss | 6.896 W | 13.792 W |
| Current Density | 4 A/mm² | 8 A/mm² |
Engineering Summary
- Wire A has 2x the conductive area of Wire B.
- Wire A has 50% of Wire B's resistance per unit length.
- Wire A has 2x the bare conductor mass per unit length of Wire B.
- At the entered current, Wire A has 50% of Wire B's current density.
AWG and nearest-AWG calculations reuse data/reference/awg.ts; no duplicate AWG table is created.
Direct mm², cmil, or kcmil inputs show nearest AWG only. Nearest AWG is not an exact equivalent unless the raw areas match.
Equivalent solid diameter is based on conductive area. It is not finished cable outside diameter and does not include insulation.
For stranded wire, enter total conductive metal area. Strand gaps and bundle outside diameter are not conductive area.
Resistance comparison uses selected material resistivity at its reference condition; WIR-012 does not apply temperature correction.
Mass comparison uses mass density, which is separate from electrical resistivity.
Current density is J = I/A only. It is not ampacity, safe-current rating, NEC compliance, or IEC compliance.
Single-conductor mode uses the entered physical conductor length with no hidden return-path multiplier.
Formula reference
Wire gauge comparison formulas
Operating formulas are included only when length and current comparison is enabled. Current density is not ampacity.
A = πd² / 4d = sqrt(4A / π)R/L = ρe / Am/L = ρm AArea Ratio = AA / ABResistance Ratio = RA / RBMass Ratio = mA / mBDifference % = (A - B) / B × 100%J = I / AR = ρeL / AVdrop = IRPloss = I²RVariable definitions
- A
- conductive cross-sectional area
- d
- equivalent solid conductor diameter
- ρe
- electrical resistivity
- ρm
- mass density
- B
- Wire B baseline for percentage differences
- J
- current density
WIR-012 Formula Audit
| Comparison Definition | Engineering comparison between selected conductor sizes, not wire-size recommendation. |
|---|---|
| Minimum Compared Wires | 2. |
| Maximum Compared Wires | 4. |
| AWG Dataset Source | data/reference/awg.ts. |
| Duplicate AWG Table Created | No. |
| Raw AWG Precision | Raw AWG area is used internally; display-rounded values are not used for formulas. |
| Area Formula | A is canonical conductive area in m². |
| Equivalent Diameter Formula | d = sqrt(4A/pi). |
| Circular Mil Source | WIR-008 circular mil conversion utilities. |
| Resistance per Length Formula | R/L = rho_e/A. |
| Mass per Length Formula | m/L = rho_m A. |
| Area Ratio Convention | Wire A / Wire B for pairwise summary. |
| Resistance Ratio Convention | Resistance of Wire A / resistance of Wire B. |
| Mass Ratio Convention | Mass of Wire A / mass of Wire B. |
| Percentage Baseline | Wire B is the baseline: (A - B)/B x 100%. |
| Material Resistivity Source | data/reference/awg.ts preset materials or explicit custom input. |
| Mass Density Source | data/reference/awg.ts preset materials or explicit custom input. |
| Reference Temperature | Preset material resistance values are nominal reference values; no temperature correction is applied. |
| Single-Conductor Length Convention | R = rhoL/A using entered physical conductor length. |
| Hidden Loop ×2 | No. |
| Operating Comparison Included | Yes, optional length and current comparison. |
| Current Density Included | Yes, J = I/A only. |
| Ampacity Included | No. |
| Safe Current Classification | No. |
| Temperature Correction Included | No. |
| Nearest AWG Policy | Nearest raw-area match, labelled nearest unless exact. |
| Stranded Wire Policy | Enter total conductive metal area; equivalent diameter is not stranded cable OD. |
| Insulation Included | No. |
| WIR-003 Boundary | Does not recommend required, minimum, best, or code-compliant wire size. |
| AWG Converter Boundary | Does not duplicate pure AWG to mm² converter intent. |
| WIR-008 Boundary | Reuses geometry/circular mil conversion. |
| WIR-009 Boundary | Uses material resistivity but does not own resistivity conversion/search intent. |
| WIR-010 Boundary | Reuses mass-density model for mass per length. |
| WIR-011 Boundary | No resistance temperature correction. |
Worked Examples
| Case | Calculation | Result |
|---|---|---|
| 2.5 mm² vs 1.25 mm² area ratio | 2.5 / 1.25 | 2x |
| 1 mm² equivalent diameter | sqrt(4e-6/pi) | 1.128379167 mm |
| 2.5 mm² copper R/L | 1.724e-8 / 2.5e-6 | 0.006896 Ω/m |
| Same resistance per meter | 0.006896 × 1000 | 6.896 mΩ/m |
| Same resistance per kilometer | 0.006896 × 1000 | 6.896 Ω/km |
| Resistance ratio | RA/RB = AB/AA | 0.5 |
| Copper 2.5 mm² mass per meter | 8960 × 2.5e-6 | 22.4 g/m |
| Copper 2.5 mm² mass per kilometer | 22.4 g/m | 22.4 kg/km |
| Mass ratio | 2.5 / 1.25 | 2x |
| Area doubled resistance | R/L ∝ 1/A | resistance per length halves |
| Area doubled mass | m/L ∝ A | mass per length doubles |
| Area doubled diameter | d ∝ sqrt(A) | diameter × sqrt(2) |
| Same size area ratio | A/A | 1 |
| Same size resistance ratio | R/R | 1 |
| Same size mass ratio | m/m | 1 |
| Same size difference | (A - A)/A | 0% |
| Area difference vs Wire B | (2.5 - 1.25)/1.25 | +100% |
| Resistance difference vs Wire B | (0.5 - 1) × 100 | -50% |
| Mass difference vs Wire B | (2 - 1) × 100 | +100% |
| 10 A through 2.5 mm² | 10 / 2.5 | 4 A/mm² |
| 10 m single conductor resistance | 0.006896 × 10 | 0.06896 Ω |
| 10 A voltage drop | 10 × 0.06896 | 0.6896 V |
| 10 A power loss | 10² × 0.06896 | 6.896 W |
| Zero current | I = 0 | Vdrop = 0, Ploss = 0, J = 0 |
| Zero length | L = 0 | R = 0, Vdrop = 0, Ploss = 0 |
| 1 ft | exact conversion | 0.3048 m |
| 1000 ft | 1000 × 0.3048 | 304.8 m |
| 1 lbm | exact conversion | 0.45359237 kg |
Engineering Notes
- WIR-012 compares candidate conductor sizes; it does not select a required wire size.
- AWG number direction is reversed from ordinary size intuition: smaller AWG number usually means larger conductor.
- AWG and metric wire sizes are different standards, so nearest AWG must not be treated as exact unless raw areas match.
- Cross-sectional area is the canonical comparison basis for AWG, mm², circular mils, and kcmil inputs.
- Equivalent solid diameter is useful for comparison, but it is not finished cable outside diameter.
- Stranded wire should be entered by total conductive metal area, not by bundle OD.
- Circular mils are based on a circular diameter in mils and must not be confused with square mils.
- Resistance per length depends on electrical resistivity and area.
- Mass per length depends on mass density and area.
- A larger conductor normally lowers resistance per length and increases conductor mass per length for the same material.
- Percentage differences are relative to Wire B, the baseline in the default pairwise summary.
- Single-conductor mode has no hidden return-path multiplier. Loop mode is explicit.
- Current density is shown only as J = I/A and is not an ampacity or code-compliance result.
- Temperature correction remains a separate WIR-011 calculation.
Common Mistakes
- Assuming a larger AWG number means a larger wire.
- Treating nearest AWG as exact equivalent.
- Using rounded AWG area internally.
- Confusing conductor diameter with cable outside diameter.
- Using stranded bundle OD as conductive area.
- Confusing circular mil with square mil.
- Forgetting resistance is inversely proportional to area.
- Assuming mass decreases when resistance decreases.
- Confusing resistivity with resistance.
- Confusing mass density with electrical resistivity.
- Using a hidden return-path ×2 without labelling it.
- Assuming twice the area means twice the ampacity.
- Calling current density a safe-current rating.
- Ignoring material when comparing resistance.
- Ignoring reference temperature for resistivity values.
- Using an ambiguous percentage baseline.
Support reference
FAQ
How do I compare two wire gauges?
Select two wire candidates, choose AWG, metric area, circular mils, or kcmil for each, then compare area, equivalent diameter, resistance per length, and mass per length.
Which is larger, AWG 10 or AWG 12?
AWG 10 is larger. In the AWG system, a smaller gauge number usually means a larger conductor diameter and larger conductive area.
Why does a smaller AWG number mean a larger wire?
AWG is a drawing-gauge system. More drawing steps produce thinner wire, so higher AWG numbers represent smaller conductors.
How do AWG and mm² compare?
AWG is a gauge series while mm² is physical cross-sectional area. The calculator compares both through canonical conductive area.
Is there an exact AWG equivalent for every mm² size?
No. Metric wire sizes and AWG sizes are different series. A nearest AWG is only nearest unless the raw areas exactly match.
What does nearest AWG mean?
Nearest AWG means the AWG record with the closest raw conductive area in the shared AWG dataset. It is not automatically an exact equivalent.
How do I compare wire cross-sectional areas?
Use Area Ratio = Area A / Area B. The page labels Wire B as the baseline for percentage differences.
How do I compare wire diameters?
The calculator converts conductive area to equivalent solid diameter using d = sqrt(4A/pi).
What is equivalent solid conductor diameter?
It is the diameter of a solid circular conductor with the same conductive area. It is not finished cable outside diameter.
Does stranded wire have the same outside diameter as solid wire?
Not necessarily. Stranded conductors have strand geometry, gaps, lay, and insulation, so equivalent solid diameter is not stranded cable OD.
What is a circular mil?
A circular mil is the area of a circle with a diameter of one mil. It is not the same as one square mil.
How does wire size affect resistance?
For the same material, resistance per length is inversely proportional to conductive area: R/L = rho/A.
How does wire size affect resistance per meter?
Doubling conductive area halves resistance per meter when material resistivity is unchanged.
How does wire size affect conductor mass?
Mass per length is proportional to area: m/L = rho_m A. Doubling area doubles bare conductor mass per length.
Why does doubling area halve resistance?
Resistance per length is rho/A, so area appears in the denominator.
Does doubling area double wire mass?
Yes for the same material density, because mass per length is density times area.
Does doubling area double ampacity?
No. Ampacity depends on installation, insulation, ambient temperature, bundling, thermal limits, and electrical codes.
Does this calculator calculate ampacity?
No. It does not calculate safe current, maximum current, NEC compliance, IEC compliance, or code-compliant wire size.
Can I compare copper and aluminum wire?
This version uses one shared material for a fair size comparison. Select copper, aluminum, or a custom material to compare all candidate sizes under that material.
Why does conductor material affect resistance?
Resistance depends on electrical resistivity. Copper and aluminum with the same area have different resistance per length.
Why does conductor material affect mass?
Mass depends on mass density. Copper and aluminum with the same area and length have different bare conductor mass.
What reference temperature is used for resistance?
Preset copper and aluminum resistivity values are nominal reference values from the shared AWG material dataset, approximately room-temperature engineering values.
Does this calculator correct resistance for temperature?
No. Use the Wire Resistance vs Temperature Calculator when conductor temperature correction is required.
Can I compare AWG with mm² directly?
Yes. AWG and direct area inputs are converted to canonical conductive area before comparison.
Does this calculator include insulation diameter?
No. Diameter means bare equivalent solid conductor diameter, not insulation, jacket, shield, or finished cable OD.
Does this calculator include insulation weight?
No. Mass is bare conductor mass only and excludes insulation, jacket, shield, filler, armor, connectors, and packaging.
How is voltage drop compared?
When operating comparison is enabled, voltage drop is Vdrop = I x R using the selected explicit length convention.
How is current density compared?
Current density is J = I/A. It is reported as an engineering comparison metric, not as a safe-current rating.
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