Ohm Square Millimetre per Metre (Ω·mm²/m)
The ohm square millimetre per metre is the resistance of a conductor 1 m long with a 1 mm² cross-section. Electricians and cable makers use it because wire sizes are given in mm²: annealed copper is 1/58 ≈ 0.01724 Ω·mm²/m.
Symbol: Ω·mm²/m (ASCII: ohm*mm2/m)
Quantity: electrical resistivity
SI relation: 1 Ω·mm²/m = 0.000001 Ω·m (exact)
Derivation: 1 Ω·mm²/m = 10⁻⁶ Ω·m (resistance in Ω of a 1 m wire with 1 mm² cross-section)
Exact: yes, by definition
Same quantity as microohm metre (µΩ·m) : the factor between them is exactly 1.
Typical uses
- Cable and wire resistance (R = ρ × length ÷ mm²)
- European conductor standards
- Electrical installation calculations
Convert ohm square millimetres per metre to other units
Open the Electrical Resistivity Converter to convert any value between all units.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Ohm Square Millimetre per Metre (Ω·mm²/m). Retrieved October 25, 2026, from https://scientificconverters.com/units/ohm-square-millimeter-per-meter/
IEEE
Scientific Converters, "Ohm Square Millimetre per Metre (Ω·mm²/m)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/units/ohm-square-millimeter-per-meter/