Electric Resistivity Converter
Convert electrical resistivity, the resistance of a material of unit length and unit cross-section, between ohm meter, ohm centimeter, ohm inch, microhm centimeter, microhm inch, circular mil ohm per foot and the CGS units. Pick two units, enter a value and read the result instantly.
Select two units to see the conversion factor.
Resistivity is a material property (Ω·m). It is not the resistance of a particular wire (Ω), and it is the inverse of conductivity (S/m), not of conductance (S).
Electric Resistivity Formula
Resistivity links the resistance of a uniform conductor to its shape: ρ = R × A ÷ L, in Ω·m. Every unit is a fixed multiple of Ω·m. Result = value × (source factor ÷ target factor). Exact building blocks: 1 Ω·cm = 0.01 Ω·m, 1 Ω·in = 0.0254 Ω·m, 1 µΩ = 10⁻⁶ Ω, 1 abohm = 10⁻⁹ Ω, 1 statohm = c² × 10⁻⁵ Ω, and 1 Ω·cmil/ft = (π/4) × (0.0000254 m)² ÷ 0.3048 m = 1.662426 × 10⁻⁹ Ω·m.
What Is Electrical Resistivity?
Electrical resistivity, written ρ (rho), is how strongly a material opposes the flow of electric current, with the effect of shape removed. It is the resistance of a piece of the material that is one meter long and has a cross-section of one square meter, so its SI unit is the ohm meter (Ω·m). Silver, copper and aluminium have very low resistivity, around 10⁻⁸ Ω·m; glass and plastics sit above 10¹² Ω·m; semiconductors fall in between and vary widely with doping and temperature.
Resistivity is what lets you predict the resistance of a conductor from its dimensions: R = ρ × L ÷ A. A 100 m run of copper wire (ρ ≈ 1.68 × 10⁻⁸ Ω·m) with a cross-section of 1 mm² (10⁻⁶ m²) has a resistance of 1.68 × 10⁻⁸ × 100 ÷ 10⁻⁶ = 1.68 Ω. Resistivity of metals rises with temperature, roughly 0.4 % per kelvin for copper near room temperature, so tabulated values are quoted at 20 °C.
Different industries use different units. Metals data often use microhm-centimeters (µΩ·cm): copper is about 1.68 µΩ·cm. Soil, water and semiconductors are usually given in ohm-centimeters (Ω·cm) or ohm-meters. In North American wire tables the unit is the circular mil ohm per foot (Ω·cmil/ft), the resistance of a wire one foot long and one circular mil in area, where annealed copper is about 10.37 Ω·cmil/ft. The abohm-centimeter and statohm-centimeter are CGS units.
Do not confuse resistivity with related quantities. Resistance (Ω) belongs to one object (Electric Resistance Converter). Conductivity (S/m) is the reciprocal of resistivity, σ = 1 ÷ ρ (Electric Conductivity Converter), and conductance (S) is the reciprocal of resistance (Electric Conductance Converter).
Supported Units
This converter supports the following 8 electric resistivity units. The last column gives the value of each unit in the base unit, Ω·m. The ohm-centimeter is a hundredth of an ohm-meter, because the length unit is in the numerator of the unit and a centimeter is a hundredth of a meter.
| Unit | Symbol | Value in Ω·m |
|---|---|---|
| Ohm meter | Ω·m | 1 |
| Ohm centimeter | Ω·cm | 0.01 |
| Ohm inch | Ω·in | 0.0254 |
| Microhm centimeter | µΩ·cm | 1e-8 |
| Microhm inch | µΩ·in | 2.54e-8 |
| Abohm centimeter | abΩ·cm | 1e-11 |
| Statohm centimeter | statΩ·cm | 8,987,551,787 |
| Circular mil ohm per foot | Ω·cmil/ft | 1.662426113e-9 |
How to Use the Electric Resistivity Converter
- Type the electric resistivity in the value box. Decimals and scientific notation such as 0.0025 or 2.5e-3 are accepted.
- Choose the From unit and the To unit.
- The result appears instantly, or press Convert Now. Very large or very small results are shown in scientific notation.
- Use Swap Units to reverse the conversion, Copy Result to copy the answer, open Show this value in all units for a full list, and Clear to start again.
Step-by-step by hand
- Find the size of each unit in the common base unit (Ω·m): 1 µΩ·cm = 1e-8 Ω·m and 1 Ω·m = 1 Ω·m.
- Divide the source size by the target size to get the conversion factor: 1e-8 ÷ 1 = 1e-8, so 1 µΩ·cm = 1e-8 Ω·m.
- Multiply by your value: 1.68 µΩ·cm × 1e-8 = 1.68e-8 Ω·m.
Resistivity cannot be negative, so only zero and positive numbers are accepted.
Common Resistivity Conversions
- Copper: 1.68 µΩ·cm equals 1.68e-8 Ω·m.
- Copper in wire tables: 10.37 Ω·cmil/ft equals 1.723935879e-8 Ω·m and 1.723935879 µΩ·cm.
- Aluminium: 2.65 µΩ·cm equals 15.94055808 Ω·cmil/ft.
- Silicon wafer: 10 Ω·cm equals 0.1 Ω·m.
- Per inch: 1 Ω·in equals 2.54 Ω·cm.
- CGS to SI: 1 abΩ·cm equals 1e-11 Ω·m.
Microhm Centimeter to Other Resistivity Units
Quick reference for frequently used values
| µΩ·cm | Ω·m | Ω·cm | Ω·cmil/ft |
|---|---|---|---|
| 1 | 1e-8 | 1e-6 | 6.015304936 |
| 1.68 | 1.68e-8 | 1.68e-6 | 10.10571229 |
| 2.65 | 2.65e-8 | 2.65e-6 | 15.94055808 |
| 5.6 | 5.6e-8 | 5.6e-6 | 33.68570764 |
| 10 | 1e-7 | 1e-5 | 60.15304936 |
| 100 | 1e-6 | 1e-4 | 601.5304936 |
| 1,000 | 1e-5 | 0.001 | 6,015.304936 |
Where and Why This Conversion Is Used
- Wire and cable design: predicting resistance and voltage drop from material and size.
- Materials science: comparing metals, alloys and heating elements, where data come in µΩ·cm.
- Semiconductors: wafer and film resistivity in Ω·cm.
- Earthing and geophysics: soil resistivity in Ω·m for grounding design.
- Reading older data: US tables in Ω·cmil/ft and CGS texts in abohm- or statohm-centimeters.
Limitations
- Resistivity changes with temperature, purity and processing. A unit conversion does not correct for it.
- The sheet resistance of a thin film, in ohms per square, is a different quantity and is not covered here.
Important Differences Between Related Electrical Measurements
- Resistivity, Ω·m is a property of the material. Resistance, Ω is that of a specific conductor: R = ρ × L ÷ A. Doubling the length doubles R but leaves ρ unchanged.
- Resistivity vs conductivity: conductivity, in S/m, is 1 ÷ ρ. A resistivity of 1.68 × 10⁻⁸ Ω·m is a conductivity of about 5.95 × 10⁷ S/m.
- Ω·m vs Ω/m: the unit is ohm times meter, not ohm per meter. Resistance per unit length (Ω/m) of a given wire is a different thing.
- Electrical vs thermal behaviour: resistivity says how well a material blocks current. Thermal conductivity in W/(m·K) says how well it passes heat. Metals tend to be good at both, but they are different quantities.
Each converter on this site changes units within one quantity only, and none of them mixes quantities. The related tools are: Charge, Current, Linear Charge Density, Surface Charge Density, Volume Charge Density, Linear Current Density, Surface Current Density, Electric Field Strength, Electric Potential, Electric Resistance, Electric Resistivity, Electric Conductance, Electric Conductivity, Electrostatic Capacitance and Inductance.