Electric Resistivity & Wire Resistance Calculator

Materials Science, ASTM Standards & Electric Resistivity Metrology

Electric Resistivity is the intrinsic material property that quantifies how strongly a substance resists electric current:

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• Universal Electric Resistivity Conversion Formulas (ASTM & SI Standards)**:

1\ Ω·m = 10^9 nΩ·m = 10^8\ μΩ·cm = 100\ Ω·cm = 6.0153 × 10^8\ Ω·cmil/ft

1\ μΩ·cm = 10^-8\ Ω·m = 10 nΩ·m = 6.0153\ Ω·cmil/ft

1\ Ω·cmil/ft = 1.662426 × 10^-9\ Ω·m = 0.16624\ μΩ·cm

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• ASTM B193 % IACS & Wire Resistance Equations**:

\% IACS = 1.7241 × 10^-8\ Ω·mρ_SI × 100 (International Annealed Copper Standard)

R = (ρ_e × L) / (A) (Conductor Resistance in Ohms, Ω)

σ_e = (1) / (ρ_e)

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• Standard Material & Conductor Benchmarks**:

• Silver (Purest Metal): 1.59 × 10^-8\ Ω·m 1.59\ μΩ·cm 108.4\% IACS

• Annealed Pure Copper: 1.68 × 10^-8\ Ω·m 1.68\ μΩ·cm 102.6\% IACS

• EC-1350 Aluminum: 2.82 × 10^-8\ Ω·m 2.82\ μΩ·cm 61.1\% IACS

• Nichrome 80/20 Alloy: 1.10 × 10^-6\ Ω·m = 110.0\ μΩ·cm Heating elements

• Intrinsic Silicon: 2,300.0\ Ω·m 2.30 × 10^5\ Ω·cm Semiconductor

• Fused Quartz Glass: 1.0 × 10^16\ Ω·m Dielectric insulator

How to Use This Calculator

Enter your Electric Resistivity (ρ_e) (e.g. 1.68e-8 in ρ_e), From Electric Resistivity Unit — choose from Ohm-meters (Ω·m - SI Base Unit), Nanoohm-meters (nΩ·m = 10⁻⁹ Ω·m - Metals), Microohm-centimeters (µΩ·cm = 10⁻⁸ Ω·m - Metallurgy), To Electric Resistivity Unit — choose from Microohm-centimeters (µΩ·cm), Nanoohm-meters (nΩ·m), Ohm-meters (Ω·m), Conductor Wire Length (L in meters) (e.g. 100 in m), Conductor Cross-Section Area (A in mm²) (e.g. 2.5 in mm²), and Material & Conductor Benchmark — choose from Custom Material Resistivity, Pure Annealed Copper (1.68 × 10⁻⁸ Ω·m = 16.8 nΩ·m) → 1.68 µΩ·cm | 102.6% IACS | 59.5 MS/m | R = 0.672 Ω (100m @ 2.5mm²), EC-1350 Electrical Aluminum (2.82 × 10⁻⁸ Ω·m) → 2.82 µΩ·cm | 61.1% IACS | 35.5 MS/m | R = 1.128 Ω. Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Total Conductor Resistance: R = rho L / A_m2 (where A_m2 = areaMm2 1e-6)

Worked Example

A utility cable engineer evaluating a 100-meter run of 2.5 mm² annealed copper wire with resistivity 1.68 × 10^-8\ Ω·m calculates the cable provides 102.6% IACS conductivity with a total loop resistance of 0.672 Ohms.

Understanding Your Result

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