# Temperature Coefficient of Resistance for Copper

The Temperature Coefficient of Resistance for Copper (near room temperature) is  0.393% per degree Celsius (C) meaning that for every 1°C rise in temperature, the resistance increases by 0.393%.

The relationship can be expressed in the formula:

R = Rref [1 + α(T – Tref)]

### Where:

 R = Conductor resistance at temperature “T” in Ohms Rref = Conductor resistance at reference temperature (Tref) in Ohms α = Temperature coefficient of resistance for the conductor material T = Conductor temperature in degrees C Tref = Reference temp at which α is specified for the conductor material in degrees C

### Example:

Assume 100 feet of 20 gauge wire has a resistance of 1.015 Ohms at 20°C (room temp). If the temperature of the wire increases by 10°C, what will the resistance of the wire be?

R = Rref [1 + α(T – Tref)]

R = 1.015 [1 + 0.00393 (30 – 20)]

R = 1.015 [1 + 0.00393 (10)]

R = 1.015 [1 + 0.0393]

R = 1.0549 Ohms

The change in resistance (R) can be expressed by a simple change to the original formula:

R = Rref [α(T – Tref)]

### Example:

Using the same assumptions as in the previous example, what will the change in the resistance of the wire be?

R = Rref [α(T – Tref)]

R = 1.015 [0.00393 (30 – 20)]

R = 1.015 [0.00393 (10)]

R = 1.015 [0.0393]

R = 0.0399 Ohms

The temperature coefficient of resistance for some common materials at 20°C:

• Copper = 0.00393
• Aluminum = 0.004308
• Iron = 0.005671
• Nickel = 0.005866
• Gold = 0.003715
• Tungsten = 0.004403
• Silver = 0.003819

Further details about temperature coefficients of resistance can be found on the All About Circuits web site.

A calculator is available on the University of Georgia HyperPhysics web site.