This electrical resistivity converter changes a material’s resistivity between ohm-meters, ohm-centimeters, ohm-inches, abohm-centimeters and statohm-centimeters. The SI unit is Ω·m. 1 Ω·cm is exactly 0.01 Ω·m, 1 Ω·in is exactly 0.0254 Ω·m, and 1 statΩ·cm is about 8.98755 × 10⁹ Ω·m.
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How to use the electrical resistivity converter
- Enter the resistivity, for example 18.2 MΩ·cm for ultrapure water, entered as 18,200,000 Ω·cm.
- In the electrical resistivity converter, choose its unit and the target unit, such as Ω·cm to Ω·m.
- Read the electrical resistivity converter result: 18,200,000 Ω·cm = 182,000 Ω·m.
For Ω·cm to Ω·m, divide by 100; for Ω·m to Ω·cm, multiply by 100.
What is electrical resistivity?
Electrical resistivity is how strongly a material resists current, independent of its size, measured in ohm-meters (Ω·m). Copper has a resistivity of about 1.7 × 10⁻⁸ Ω·m, while glass is many orders of magnitude higher.
Conversion formula
The electrical resistivity converter stores every unit as a multiple of the base unit, the ohm meter (Ω·m). To convert:
value in target unit = value × (factor of source unit ÷ factor of target unit)
where each factor is the size of the unit in ohm meters.
Common electrical resistivity conversions
| From | To | 1 unit equals |
|---|---|---|
| ohm meter (Ω·m) | ohm centimeter (Ω·cm) | 100 Ω·cm |
| ohm centimeter (Ω·cm) | ohm meter (Ω·m) | 0.01 Ω·m |
Electrical resistivity converter worked example
Convert 25 ohm meters to ohm centimeters:
- Factor of Ω·m = 1 Ω·m
- Factor of Ω·cm = 0.01 Ω·m
- 25 × 1 ÷ 0.01 = 2,500 Ω·cm
Electrical resistivity unit reference
| Unit | Symbol | Group | Equals (Ω·m) |
|---|---|---|---|
| Ohm Meter | Ω·m | SI | 1 |
| Ohm Centimeter | Ω·cm | SI | 0.01 |
| Ohm Inch | Ω·in | US/Imperial | 0.0254 |
| Abohm Centimeter | abΩ·cm | CGS-EMU | 1 × 10−11 |
| Statohm Centimeter | statΩ·cm | CGS-ESU | 8,987,551,787 |
Reverse factors for each electrical resistivity unit
The reference table gives each unit in ohm meters. To go the other way, divide by that factor; the list below does the division for you.
- Ohm Centimeter (Ω·cm), SI: 1 Ω·cm = 0.01 Ω·m, so 1 Ω·m = 100 Ω·cm.
- Ohm Inch (Ω·in), US/Imperial: 1 Ω·in = 0.0254 Ω·m, so 1 Ω·m = 39.37008 Ω·in.
- Abohm Centimeter (abΩ·cm), CGS-EMU: 1 abΩ·cm = 1 × 10−11 Ω·m, so 1 Ω·m = 1 × 1011 abΩ·cm.
- Statohm Centimeter (statΩ·cm), CGS-ESU: 1 statΩ·cm = 8,987,552 Ω·m, so 1 Ω·m = 1.11265 × 10−7 statΩ·cm.
Resistivity to conductivity
Conductivity is the reciprocal of resistivity: σ = 1 ÷ ρ, in S/m when ρ is in Ω·m. This is the electrical resistivity to conductivity converter step:
| Material | ρ (Ω·m) | ρ (Ω·cm) | σ (S/m) |
|---|---|---|---|
| Annealed copper, IACS standard at 20 °C | 1.7241 × 10⁻⁸ | 1.7241 × 10⁻⁶ | 5.8 × 10⁷ |
| Ultrapure water at 25 °C | 182,000 | 18,200,000 | 5.495 × 10⁻⁶ |
The International Annealed Copper Standard defines 100% IACS as 1/58 Ω·mm²/m. 18.2 MΩ·cm is the familiar reading for ASTM Type I reagent water.
Resistance of a wire from resistivity
A conductor’s resistance is R = ρ × L ÷ A. 100 m of 2.5 mm² copper at the IACS value has R = 1.7241 × 10⁻⁸ × 100 ÷ 2.5 × 10⁻⁶ ≈ 0.690 Ω. Resistivity rises with temperature in metals, so state the temperature. Convert the result with the electrical resistance converter and the reciprocal with the electrical conductivity converter.
Ohm-circular mil per foot
North American wire tables give resistivity in Ω·cmil/ft. Copper at 20 °C, about 1.68 × 10⁻⁸ Ω·m, is roughly 10.1 Ω·cmil/ft in the electrical resistivity converter. The annealed copper standard, 1.7241 × 10⁻⁸ Ω·m, is about 10.37. Many older formulas use K = 10.4 for copper, which comes from this standard.
Soil resistivity for grounding and corrosion work is usually in Ω·cm. 100 Ω·m is 10,000 Ω·cm. Soils below about 2,000 Ω·cm are often rated as corrosive to buried steel, though local standards differ.
To find the resistance of a wire run, multiply resistivity by length and divide by cross-sectional area, keeping all three in matching units. With Ω·cmil/ft, the length goes in feet and the area in circular mils. With Ω·m, use meters and square meters. Mixing the two sets is the usual source of answers that are off by large factors.
Related converters and calculators
Related electrical tools:
- Electrical conductivity converter: S/m and mS/cm
- Electrical resistance converter: Ω, kΩ, MΩ
- Electrical conductance converter: S and µS
- Voltage drop calculator: wire runs
- Current density converter: A/m²
Sources
NIST Special Publication 811, Appendix B; NIST Handbook 100: Copper Wire Tables.
Questions about this calculator
What is the SI unit of resistivity?
The ohm-meter (Ω·m).
How do I convert Ω·cm to Ω·m?
Divide by 100. For example, 500 Ω·cm = 5 Ω·m.
How do I convert resistivity to conductivity?
Take the reciprocal: σ = 1 ÷ ρ. 2 × 10⁻⁸ Ω·m is 5 × 10⁷ S/m.
What is the resistivity of copper?
The IACS standard for annealed copper is 1.7241 × 10⁻⁸ Ω·m at 20 °C.
What is 18.2 MΩ·cm in Ω·m?
182,000 Ω·m.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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