Thermal Expansion Converter

Length/Length/Kelvin (1/K)

The SI unit of linear thermal expansion coefficient. It represents the fractional change in length per unit change in absolute temperature (in kelvin). α = ΔL / (L₀ × ΔT).

Common uses: International standards, scientific research, material specifications.

Length/Length/Degree Celsius (1/°C)

Thermal expansion coefficient using Celsius temperature intervals. Since Kelvin and Celsius have the same interval size, 1/K = 1/°C.

Note: Equivalently expressed as the fractional change in length per degree Celsius.

Length/Length/Degree Fahrenheit (1/°F)

Thermal expansion coefficient using Fahrenheit temperature intervals. Since a 1°C change equals a 1.8°F change, 1/°F = 1.8 × (1/°C).

Conversion factor: 1/°F = 1.8 × (1/K)

Length/Length/Degree Rankine (1/°R)

Thermal expansion coefficient using Rankine temperature intervals. The Rankine scale has the same intervals as Fahrenheit. 1/°R = 1.8 × (1/K).

Application: Used in some engineering calculations in the United States.

Length/Length/Degree Reaumur (1/°r)

Thermal expansion coefficient using Reaumur temperature intervals. Since a 1°C change equals a 0.8°r change, 1/°r = 0.8 × (1/°C).

Note: Rarely used in modern applications but found in historical engineering texts.

Typical Linear Expansion Coefficients

• Aluminum: 23 × 10⁻⁶ /K
• Copper: 16.5 × 10⁻⁶ /K
• Steel: 11-13 × 10⁻⁶ /K
• Glass: 5-10 × 10⁻⁶ /K
• Concrete: 10-14 × 10⁻⁶ /K
• Invar (Fe-Ni alloy): 1-2 × 10⁻⁶ /K

Thermal Expansion Formula

The linear thermal expansion is calculated using: ΔL = α × L₀ × ΔT

• ΔL: Change in length
• α: Linear expansion coefficient
• L₀: Original length
• ΔT: Change in temperature