Convert electric resistivity between Ω·m, Ω·cm, µΩ·cm, nΩ·m, Ω·mm²/m, and Ω·cmil/ft, with conductivity and simple resistance checkpoints.
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Presets
Scope note
All values reduce to an ohm-metre baseline first, then expand into engineering-friendly forms used for materials, conductors, and wire sizing.
Resistance check
Resistivity is a material property. The resistance checkpoint below uses R = ρL/A for a one-metre conductor with a 1 mm² cross-section, so you can see why geometry still matters after the unit conversion.
Result
1.724 µΩ·cm equals 1.724e-8 Ω·m and fans out through the grouped engineering scales below.
Material-property interpretation
This value behaves like a material resistivity reference, not the finished resistance of a wire, trace, busbar, or soil path. Conductivity is the reciprocal of resistivity, while the one-metre checkpoint applies a simple geometry so the converted number has a practical scale.
Formula
R = ρL / A and σ = 1 / ρ
For the 1 m x 1 mm² checkpoint, this input gives 0.01724 Ω before temperature, stranding, alloy, or tolerance corrections.
Metric engineering units
Core resistivity values used in materials, electronics, and lab references.
Ohm metres
Ω·m reference
1.724e-8 Ω·m
Ohm centimetres
Ω·cm reference
1.724e-6 Ω·cm
Ohm square millimetres per metre
Ω·mm²/m reference
0.01724 Ω·mm²/m
Precision micro scales
Small values are often easier to read in microohm notation for conductors and alloys.
Microohm metres
µΩ·m reference
0.01724 µΩ·m
Microohm centimetres
µΩ·cm reference
1.724 µΩ·cm
Nanohm metres
nΩ·m reference
17.24 nΩ·m
Wire-design constant
The ohm-circular-mil/foot scale matches cable and conductor sizing calculations.
Ohm circular-mil per foot
Ω·cmil/ft reference
10.3704 Ω·cmil/ft
Conversions
An electric resistivity converter rewrites one resistivity value across the material-property units common in engineering and the conductor constant used in wire-design references. It is useful when a table quotes Ω·m, a lab note uses µΩ·cm, or a cable calculation expects Ω·cmil/ft instead.
This page converts a non-negative resistivity across Ω·m, Ω·cm, Ω·mm²/m, µΩ·m, µΩ·cm, nΩ·m, and Ω·cmil/ft.
Those units cover broad materials work, small conductor-property scales, metal and alloy values that are easier to read in nanohm-metres, and the wire-design constant that still appears in cable and conductor sizing references.
The converter first resolves the entered unit into ohm-metres. Every other result is then just the same resistivity restated in a scale that may be more practical for the source you are reading.
Keeping the Ω·m baseline visible helps when you move between materials-property tables and wire-design constants without losing track of the actual resistivity behind the notation.
1 Ω·cm = 0.01 Ω·m
Centimetre-based resistivity is the same quantity expressed on a shorter length basis.
1 Ω·mm²/m = 10^-6 Ω·m
The square-millimetre engineering form is common in conductor and cable work.
1 µΩ·m = 10^-6 Ω·m; 1 µΩ·cm = 10^-8 Ω·m
Micro scales make small conductor-property values easier to compare.
1 nΩ·m = 10^-9 Ω·m
Nanohm-metres are convenient for very conductive metals and alloys.
Resistivity is a material property. Resistance is the total effect for a particular path with a particular length and cross-section. Changing units here does not turn a property value into the resistance of a finished part or wire run.
That distinction matters because geometry can dominate the actual resistance seen in a circuit even when the material resistivity stays fixed.
The calculator now keeps a simple geometry checkpoint beside the conversion: resistance for a one-metre path with a 1 mm² cross-section. That checkpoint uses the standard R = ρL/A relationship so the converted material value is easier to interpret without pretending it replaces a full cable, trace, or busbar design.
R = ρL / A
R is resistance, ρ is resistivity, L is path length, and A is cross-sectional area.
σ = 1 / ρ
Conductivity is the reciprocal of resistivity when both are expressed in coherent SI units.
Material-property tables often quote conductive metals in µΩ·cm, nΩ·m, Ω·mm²/m, or Ω·cmil/ft depending on the reference. The copper and aluminium presets give realistic starting points for comparing how the same property value looks across those notations.
Treat those presets as reference examples, not universal design values. Actual conductor resistance depends on alloy, temperature, stranding, cold-work, purity, surface condition, and the physical length and area of the conductor. For precision work, use the value from the material certificate, standard, or measured sample rather than a generic preset.
Ω·cmil/ft is included because American wire and cable references often use circular mil area with foot length. The calculator converts that constant through the exact circular-mil area definition and foot-to-metre relationship before reporting the equivalent Ω·m value.
This is useful when a table gives a conductor resistivity constant in Ω·cmil/ft but the rest of your calculation is metric. It still does not choose a wire size, apply ampacity rules, or estimate voltage drop; it only moves the material property into the same unit system.
This calculator does not estimate path resistance, temperature coefficients, conductivity, or voltage drop from a resistivity value. It converts the resistivity quantity itself between units only.
Use it as a planning and educational reference. If the next step depends on conductor length, area, or circuit behaviour, switch to the calculator that models that relationship directly.
Frequently asked questions
Because many conductor and alloy resistivity values are very small, and microohm-centimetre notation is often easier to read and compare than the equivalent decimal in ohm-metres.
It is a wire-design resistivity constant used in conductor sizing and legacy cable calculations. It is included here so those references can be compared directly against modern metric property units.
No. Actual resistance depends on resistivity together with conductor length and cross-sectional area. This page only converts resistivity units.
The usual relationship is R = ρL / A, where R is resistance, ρ is resistivity, L is conductor length, and A is cross-sectional area. This converter uses that formula only for a simple one-metre by 1 mm² checkpoint; real conductor calculations need the actual geometry and temperature basis.
Conductivity is the reciprocal of resistivity when the units are coherent. In SI terms, conductivity in S/m is 1 divided by resistivity in Ω·m. That is why a low-resistivity metal has high conductivity.
Nanohm-metres are convenient for highly conductive metals because their Ω·m values are very small. For example, a value around 10 to 30 nΩ·m is easier to read than writing the same value as a long decimal in Ω·m.
Yes, but convert it first so the rest of the calculation uses one coherent unit basis. This converter translates Ω·cmil/ft into Ω·m and Ω·mm²/m, which helps when a wire-design reference is imperial but your length and area data are metric.
Yes. Many conductor resistivity values are quoted at a reference temperature, and metals usually become more resistive as temperature rises. This converter does not apply a temperature coefficient; it converts the value you enter.
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