Convert Circular Mil Ohm/Foot to Microhm Inches
Circular Mil Ohm/Foot (cmil·Ω/ft) to Microhm Inch (μΩ·in) electric resistivity conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 cmil·Ω/ft = 0.065449847 μΩ·in
1 Circular Mil Ohm/Foot = 0.065449847 Microhm Inches
1 Microhm Inch = 15.278875 Circular Mil Ohm/Foot
1 cmil·Ω/ft in every supported unit
Conversion chart: Circular Mil Ohm/Foot to Microhm Inches
Conversion table
| Circular Mil Ohm/Foot (cmil·Ω/ft) | Microhm Inch (μΩ·in) |
|---|---|
| 0.01 cmil·Ω/ft | 0.00065449847 μΩ·in |
| 0.1 cmil·Ω/ft | 0.0065449847 μΩ·in |
| 1 cmil·Ω/ft | 0.065449847 μΩ·in |
| 2 cmil·Ω/ft | 0.13089969 μΩ·in |
| 3 cmil·Ω/ft | 0.19634954 μΩ·in |
| 5 cmil·Ω/ft | 0.32724923 μΩ·in |
| 10 cmil·Ω/ft | 0.65449847 μΩ·in |
| 20 cmil·Ω/ft | 1.3089969 μΩ·in |
| 50 cmil·Ω/ft | 3.2724923 μΩ·in |
| 100 cmil·Ω/ft | 6.5449847 μΩ·in |
| 1000 cmil·Ω/ft | 65.449847 μΩ·in |
Circular Mil Ohm/Foot (cmil·Ω/ft)
Definition: A resistivity unit unique to the American wire industry, expressing resistivity as ohms per foot of length per circular mil of cross-sectional area — the circular mil being the standard US unit for wire cross-section (the area of a circle one mil, or 0.001 inch, in diameter).
History: It developed directly out of the American Wire Gauge (AWG) system, where wire cross-sections are conventionally measured in circular mils rather than square millimeters, so expressing resistivity in matching units let engineers compute a wire's resistance directly from its AWG size and length without an extra area-unit conversion step.
Current use: Still the standard resistivity unit in US wire and cable engineering and National Electrical Code ampacity tables — copper's resistivity is commonly quoted as about 10.66 Ω·cmil/ft at 20°C.
Microhm Inch (μΩ·in)
Definition: The US customary counterpart to microhm-centimeter, combining the microhm with the inch as the reference length for reporting metal and alloy resistivity in imperial-unit engineering documents.
History: Extended from microhm-centimeter for American wire, cable, and metal-stock industries that specify dimensions in inches rather than centimeters, keeping resistivity figures consistent with the rest of the drawing or datasheet.
Current use: Occasionally seen in US wire, cable, and sheet-metal industry documentation reporting conductor material resistivity alongside inch-based dimensional specifications.
Supported Units
| Unit | Symbol | In Ohm Meter |
|---|---|---|
| Ohm Meter | Ω·m | 1 Ω·m |
| Ohm Centimeter | Ω·cm | 0.01 Ω·m |
| Ohm Inch | Ω·in | 0.0254 Ω·m |
| Microhm Centimeter | μΩ·cm | 1E-08 Ω·m |
| Microhm Inch | μΩ·in | 2.54E-08 Ω·m |
| Abohm Centimeter | abΩ·cm | 1E-11 Ω·m |
| Statohm Centimeter | statΩ·cm | 8.98755E+09 Ω·m |
| Circular Mil Ohm/Foot | cmil·Ω/ft | 1.66243E-09 Ω·m |
About These Parameters
- Value
- The electric resistivity value you want to convert, expressed in the "From" unit. Accepts decimals, and can represent anything from a metal's resistivity in microhm-centimeters to a semiconductor's resistivity in ohm-centimeters.
- From Unit
- The unit your input value is currently measured in — a wafer datasheet's ohm-centimeter rating, a wire table's circular-mil-ohm-per-foot figure, or an older CGS unit like abohm-centimeter or statohm-centimeter.
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly, which is handy when moving a material spec into the units used in your own design calculations.
How Electric Resistivity Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to the ohm-meter. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Circular Mil Ohm/Foot → Microhm Inch: multiply by 0.065449847. For example, 1 cmil·Ω/ft × 0.065449847 = 0.065449847 μΩ·in.
Resistivity vs. Resistance
Resistance (in ohms) tells you how much a specific object opposes current, but that number depends on the object's length and cross-sectional area as much as it depends on what it's made of — double a wire's length and its resistance doubles; double its cross-section and resistance halves. Resistivity strips geometry out of the equation entirely, describing only the material itself: copper is always about 1.68×10⁻⁸ Ω·m regardless of whether it's a hair-thin wire or a thick busbar. That makes resistivity the number engineers actually compare when choosing between materials, while resistance is what they calculate afterward once a specific shape is chosen.
Why So Many Length-Based Variants
Because resistivity is measured "per unit length" in some form, every length unit in common engineering use has spawned its own resistivity unit: centimeters gave the semiconductor industry ohm-centimeter and metallurgy microhm-centimeter, inches gave American manufacturing ohm-inch and microhm-inch, and the circular mil — the standard cross-sectional-area unit for American Wire Gauge tables — combined with the foot to give wire engineers circular-mil-ohm-per- foot, a unit that lets them compute a wire's resistance directly from its AWG size without an extra area conversion. The CGS-era abohm-centimeter and statohm-centimeter round out the list as relics of 19th-century electromagnetic and electrostatic unit systems.
Example
An electric resistivity of 1 cmil·Ω/ft equals 0.065449847 μΩ·in. For scale, copper's resistivity is about 1.68×10⁻⁸ Ω·m (1.68 μΩ·cm), a typical doped silicon wafer for integrated circuits might run anywhere from about 0.001 to 100 Ω·cm depending on doping level, and a good electrical insulator like glass can exceed 10¹² Ω·m.
Frequently Asked Questions
How many Microhm Inches are in 1 Circular Mil Ohm/Foot?
1 Circular Mil Ohm/Foot (cmil·Ω/ft) equals exactly 0.065449847 Microhm Inches (μΩ·in).
What's the difference between resistivity and resistance?
Resistivity (ohm-meters) is a property of the material alone, unaffected by shape or size. Resistance (ohms) is the property of one specific object, and depends on that material's resistivity plus the object's length and cross-sectional area. See the separate Electric Resistance Converter for that quantity.
Why do semiconductor datasheets use ohm-centimeters instead of ohm-meters?
Silicon wafer resistivity values typically fall in a range — roughly 0.001 to 100 ohm-centimeters — that reads more naturally in centimeters than in the much smaller numbers meters would produce. The convention stuck from the CGS era and remains the semiconductor industry standard today, even though the rest of SI has moved to meters.
What is a circular mil, and why does wire resistivity use it?
A circular mil is the area of a circle exactly one mil (0.001 inch) in diameter — the standard cross-sectional-area unit used throughout the American Wire Gauge (AWG) system. Expressing wire resistivity in ohms per circular mil per foot lets engineers compute a wire's resistance straight from its AWG size and length, without a separate step to convert circular mils into square inches or square millimeters first.
Are abohm-centimeter and statohm-centimeter still used?
Almost never in modern engineering. They're the resistivity units of the 19th-century CGS electromagnetic (EMU) and electrostatic (ESU) systems respectively, and survive mainly in historical physics literature and theoretical derivations written in Gaussian units, well before the SI's ohm-meter became the near-universal standard.