electric resistivity converter
Convert electrical resistivity across Ohm-meters, Ohm-centimeters, and circular mil-foot. Reference resistivity charts for conductors.
Unit ConvertersEquivalent Conductivity (S/m)
Material Identifier
How to Use the Electric Resistivity Converter
Step-by-step instructions for converting resistivity units, identifying matching materials, and analyzing soil earthing conditions.
Enter Resistivity in Any Unit
Type a value into any unit box: Ohm-meter (Ω·m), Ohm-centimeter (Ω·cm), Microohm-cm (µΩ·cm), or Ohm-mm²/m (Ω·mm²/m).
Instant Multi-Unit Synchronization
All equivalent units across SI, CGS, and cable engineering standards update automatically in real time.
Check Conductivity Mirror (S/m)
Read the inverse electrical conductivity value instantly in Siemens per meter (S/m) using the formula σ = 1 / ρ.
Identify Matching Physical Materials
Inspect the Material Identifier card to see the closest matching substance among conductors, semiconductors, or insulators.
Analyze Grounding & Soil Resistivity
For values between 5 and 10,000 Ω·m, the tool evaluates earthing performance and predicts soil type (clay, loam, sand, rock).
Toggle Scientific Notation & Copy Data
Switch between exponential and standard decimal formats, then click Copy Material Spec to save results to your clipboard.
Frequently Asked Questions (FAQ)
Physical definitions, conductivity reciprocal, cable engineering units, grounding standards, and material classifications.
Q:What is electrical resistivity (ρ) and how does it differ from electrical resistance (R)?
Electrical resistance (R, measured in Ohms, Ω) is an extrinsic property of a specific object that depends on its physical shape and size (R = ρ × L / A). Electrical resistivity (ρ, in Ohm-meters, Ω·m) is an intrinsic physical property of the material itself, quantifying how strongly it opposes electrical current regardless of geometry. A thick copper rod and thin copper wire share the same resistivity (1.68 × 10⁻⁸ Ω·m) but have very different total resistances.
Q:How does electrical conductivity (σ) relate to electrical resistivity (ρ)?
Electrical conductivity (σ, measured in Siemens per meter, S/m) is the exact mathematical reciprocal of resistivity: σ = 1 / ρ. Materials with exceptionally low resistivity (like silver with 1.59 × 10⁻⁸ Ω·m) exhibit ultra-high conductivity (6.30 × 10⁷ S/m), while electrical insulators have minute conductivity values.
Q:Why is Ω·mm²/m widely used in electrical engineering alongside Ω·m?
In practical cable installation, conductor lengths are measured in meters (m) while cross-sectional areas are expressed in square millimeters (mm²). Using Ω·mm²/m (where 1 Ω·m = 10⁶ Ω·mm²/m) simplifies resistance calculations to R = ρ × L / A directly without needing exponent conversion. For example, annealed copper is conveniently expressed as 0.0168 Ω·mm²/m.
Q:How does temperature alter electrical resistivity in conductors vs. semiconductors?
In metallic conductors, resistivity increases with temperature because thermal lattice vibrations scatter electrons (positive temperature coefficient, α ≈ +0.00393/°C for copper). In semiconductors (like silicon) and carbon, resistivity decreases as temperature rises because thermal energy excites more valence electrons across the bandgap into the conduction band (negative temperature coefficient).
Q:What is soil resistivity and why is it essential for electrical earthing / grounding?
Soil resistivity measures how well earth ground conducts fault current and lightning strikes, typically ranging from 10–50 Ω·m (moist clay) to over 3,000 Ω·m (dry rock). Power substations and electrical panels require low ground resistance (often < 5 Ω or < 25 Ω under IEEE and NEC standards). Low soil resistivity ensures rapid, safe dissipation of electrical faults into the ground.
Q:What defines the resistivity boundaries between conductors, semiconductors, and insulators?
Materials span more than 30 orders of magnitude in resistivity: conductors have ρ < 10⁻⁶ Ω·m (metals like silver, copper, aluminum); semiconductors fall between 10⁻⁵ and 10⁵ Ω·m (graphite, silicon, germanium); and electrical insulators exceed 10⁸ Ω·m up to 10²³ Ω·m (glass, rubber, Teflon).
Q:How is soil resistivity measured in the field using the Wenner 4-pin method?
Standardized by IEEE 81, the Wenner 4-pin test places four equally spaced electrodes in a straight line at depth distance 'a'. An AC current (I) is injected through the outer two pins while the resulting voltage drop (V) is measured across the inner two pins. The apparent soil resistivity is calculated as ρ = 2πa(V/I), probing earth layers down to depth 'a'.
- ρ (Rho): Electrical Resistivity (Ω·m).
- R: Electrical Resistance (Ohms).
- A: Cross-sectional Area (m²).
- L: Length of the specimen (m).
- σ (Sigma): Electrical Conductivity (S/m).
Electric resistivity converter Table
| Unit | Ω·m | Ω·cm | μΩ·m | μΩ·cm |
|---|---|---|---|---|
| 1 Ω·m | 1 | 100 | 1,000,000 | 100,000,000 |
| 1 Ω·cm | 0.01 | 1 | 10,000 | 1,000,000 |
| 1 μΩ·m | 0.000001 | 0.0001 | 1 | 100 |
| 1 μΩ·cm | 0.00000001 | 0.000001 | 0.01 | 1 |
What is electric resistivity converter?
| Interface Element | Scientific Function | Practical Application |
|---|---|---|
| Scientific Notation | Number Formatting | Condenses long strings of zeros into clear exponents for professional documentation. |
| EQUIVALENT CONDUCTIVITY (S/m) | Inverse Calculation | Instantly flips the specific resistance into specific conductance for alternating formulas. |
| MATERIAL IDENTIFIER | Database Matching | Analyzes the input to suggest what physical material or soil type matches that exact resistivity. |
| Copy Material Spec | Data Export | Copies the entire set of converted units and material names to your device's clipboard. |