# Calculate the temperature dependence of a resistor

Online calculator for calculating the temperature dependence of a resistor

## Calculate the temperature dependence

The resistance of all materials is more or less dependent on the temperature. On this page, the value of a resistor at a certain temperature can be calculated using the temperature coefficient.

The temperature coefficient α gives the change in resistance for one Resistance of 1 ohm when heated by one K (Kelvin) or degree Celsius.

temperature dependence online calculator

 Input Resistance at 20 °C mΩ Ω kΩ MΩ Temperature coefficient α Temperature change °C Resultat Change of resistance Calculated Resistance Decimal places 0 1 2 3 4 6 8 10

## Formulas of temperature dependence of a resistor

The resistance of all materials is more or less dependent on the temperature. Copper conducts better when cold. That is why copper and other metals are classed as PTC thermistors. Coal conducts better when it is warm. Therefore coal is one of the hot conductors.

The temperature coefficient $$α$$ gives the change in resistance for one Resistance of 1 ohm when heated by one $$K$$ (Kelvin) or degree Celsius.

#### Example

PTC thermistors have a positive temperature coefficient and are therefore called PTC

Copper 99.9%: 0.00393
Aluminium 99.9%: 0.004

NTC thermistors have a negative temperature coefficient and are therefore called NTC

Coal: -0.00004
Constantan: -0.00008..+0.00004

There are also slightly different values for the temperature coefficients on the Internet. The value depends, among other things, on the purity of the material.

### Resistance change formulas

The change in resistance is calculated:

$$\displaystyle ΔR=α · Δ ϑ · R_k$$

The resistance in the warm state is calculated:

$$\displaystyle R_w=R_k + ΔR$$

or:

$$\displaystyle R_w=R_k(1+α· Δϑ)$$

#### Legend

 $$\displaystyle Rk$$ Resistance at 20 °C Ω $$\displaystyle α$$ Temperature coefficient $$\displaystyle Δϑ$$ Temperature change °C; K $$\displaystyle ΔR$$ Change of resistance Ω $$\displaystyle R_w$$ Resistance when warm Ω

For some metals the resistance is close to absolute zero (-273.16 ° C) at 0 ohms. We speaks here of superconductors (e.g. aluminum, lead, tin)

The formula $$\displaystyle R_w=R_k(1+α· Δϑ)$$ only applies up to about $$\displaystyle Δϑ = 200K$$