Material Calculator - Specific Resistance

Calculator for the electrical resistance in ohm from specific resistance (electrical resistivity), diameter or cross-section and length, for example for a wire made from a certain material. The specific resistance refers to the material, it can change with temperature. When the diameter is entered, a circular cross-section is assumed. If the cross-section is not round, then this should be specified instead of the diameter. You can choose a material or enter the specific resistance directly. Diameter and cross-section count as one value. Enter three values, choose the units and press Calculate.

Example: a 1.5 millimeters thick copper cable (cross-section 1.767 mm²) with a length of 4 meters has an electrical resistance of 38.48 milliohms.

The specific resistance is a material constant that depends on the temperature. If an electric current flows through a conductive material that has an electrical resistance, the temperature of the conductor increases and with it the specific resistance changes. This change can be so large, especially with strong currents and high resistances, that it has a noticeable influence and therefore makes an exact calculation very difficult. For example, if the temperature in a copper cable rises from 20 degrees Celsius to 40 degrees, the specific resistance increases by around 8 percent. For this to happen, for example, a current of one ampere must flow through the copper cable for around a minute if it has a resistance of one ohm. This resistance would apply to the copper cable from the above example with a length of 104 meters. The temperature change would cause the resistance to rise to 1.08 ohms.