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Electric Resistivity Converter

Science

Convert electric resistivity between ohm-metres, ohm-centimetres, and ohm-square millimetres per metre — used for wire and material selection.

Reviewed by the thecalcu.com team · Last updated July 23, 2026

From
To
All conversionsfor 1 Ohm-Square Millimetres per Metre (Ω·mm²/m)
Ohm-Metres (Ω·m)0.000001
Ohm-Centimetres (Ω·cm)0.0001
Microhm-Centimetres (µΩ·cm)100
Ohm-Square Millimetres per Metre (Ω·mm²/m)1

What is a Electric Resistivity?

The Electric Resistivity Converter converts electric resistivity between ohm-metres (SI), ohm-centimetres and microhm-centimetres (metric/CGS-adjacent), and ohm-square-millimetres-per-metre (the standard wire specification unit). Electric resistivity is an intrinsic material property describing how strongly a material resists current flow, independent of its specific shape, distinct from resistance, which also depends on a conductor's dimensions.

Enter a value in any supported unit and the converter calculates the equivalent instantly. For the related dimension-dependent quantity, see the Electric Resistance Converter.

Why Use an Electric Resistivity Converter?

Wire and cable manufacturers specify conductor resistivity in Ω·mm²/m (matching how wire cross-sections are measured), while materials science references and SI-based calculations use Ω·m, and some scientific literature uses the smaller-scale microhm-centimetre. Comparing material properties across these unit conventions requires accurate conversion.

Who Should Use This Converter?

  • Electrical engineers selecting and comparing conductor materials for wiring or busbar design.
  • Materials scientists characterising and comparing new conductive material properties.
  • Semiconductor engineers working with doped material resistivity specifications across unit conventions.
  • Electrical engineering students converting resistivity values for materials science or circuits coursework.

What Insights Does the Electric Resistivity Converter Give You?

The main output is the converted value in your chosen target unit, calculated precisely from the fixed multiplier relationship between units. Because resistivity spans an enormous range across material types, from excellent conductors to near-perfect insulators, the converter helps you sanity-check whether a value is realistic for the type of material involved.

How to use this Electric Resistivity calculator

  1. Choose your starting unit from the source dropdown, for example, "Ohm-Square Millimetres per Metre".
  2. Enter the numeric value you want to convert in the input field.
  3. Choose your target unit from the destination dropdown, for example, "Ohm-Metres (Ω·m)".
  4. Read the converted result, which updates instantly as you type or change units.
  5. Use the swap (⇅) button if you need to reverse the conversion direction.
  6. Use the copy button to grab the result for a conductor selection or materials comparison.
Show formula & methodology ↓Show less ↑

Formula & Methodology

The converter's base unit is ohm-metres (Ω·m). Every supported unit has a fixed multiplier:

- 1 ohm-centimetre (Ω·cm) = 0.01 Ω·m
- 1 microhm-centimetre (µΩ·cm) = 1 × 10⁻⁸ Ω·m
- 1 ohm-square-millimetre per metre (Ω·mm²/m) = 0.000001 Ω·m

Any conversion follows:

Result = Input × (toBase of source unit ÷ toBase of target unit)

Worked example, converting copper's resistivity of 0.0172 Ω·mm²/m to Ω·m:

Result = 0.0172 × 0.000001 = 0.0000000172 Ω·m (1.72 × 10⁻⁸ Ω·m)

This matches the standard reference value for copper's resistivity expressed in SI base units.

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Frequently Asked Questions

What is electric resistivity?
Electric resistivity is an intrinsic material property measuring how strongly a material resists electric current flow, independent of the specific shape or size of a sample, unlike resistance, which depends on a conductor's length and cross-sectional area as well as its material.
How do I convert Ω·mm²/m to Ω·m?
Divide the Ω·mm²/m value by 1,000,000, since one ohm-square-millimetre-per-metre equals one-millionth of an ohm-metre. Enter your value with 'Ohm-Square Millimetres per Metre' as the source and 'Ohm-Metres (Ω·m)' as the target to apply this automatically.
Why is Ω·mm²/m the standard unit for wire resistivity specifications?
Wire cross-sections are naturally measured in square millimetres and lengths in metres, so Ω·mm²/m produces conveniently-sized numbers for typical conductor materials (copper's resistivity is about 0.0172 Ω·mm²/m) compared to the much smaller numbers Ω·m would produce for the same material.
How does resistivity relate to resistance?
Resistance equals resistivity multiplied by length and divided by cross-sectional area (R = ρL/A), resistivity is the fixed material property, while resistance also depends on the specific conductor's dimensions. See the [Electric Resistance Converter](/electric-resistance-converter/) for the resulting resistance quantity.
What is copper's resistivity, and why is it a common reference value?
Copper has a resistivity of approximately 1.72 × 10⁻⁸ Ω·m (or 0.0172 Ω·mm²/m) at room temperature, making it one of the best commercially practical conductors, this value is frequently used as a reference point when evaluating alternative conductor materials.
How does resistivity relate to conductivity?
Electrical conductivity is the mathematical reciprocal of resistivity (conductivity = 1 ÷ resistivity), a material with low resistivity has high conductivity, and vice versa. See the [Electric Conductivity Converter](/electric-conductivity-converter/) for that inversely related quantity.
Does resistivity change with temperature?
Yes, most conductors' resistivity increases with temperature (due to increased atomic vibration impeding electron flow), which is why precise resistivity values are always specified at a particular reference temperature, commonly 20°C or 25°C.
Why do semiconductors have such a wide range of resistivity values?
Semiconductor resistivity can be adjusted over many orders of magnitude through doping (adding controlled impurities), which is precisely why semiconductors are useful for building transistors and other electronic devices with tunable electrical properties.
What's a typical resistivity range across material types?
Conductors like copper and silver have resistivity around 10⁻⁸ Ω·m, semiconductors range from roughly 10⁻⁵ to 10⁸ Ω·m depending on doping, and insulators can exceed 10¹⁶ Ω·m, a span of over 20 orders of magnitude across the full range of materials.
Who typically needs to convert electrical resistivity units?
Electrical engineers selecting conductor materials for wiring or busbar design, materials scientists characterising new conductive materials, and semiconductor engineers working with doped material resistivity specifications all commonly need accurate resistivity unit conversion.
Also known as
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