What this converter does
This converter turns the coefficient of thermal expansion between µm/m·°C (the same as ppm/°C), in/in·°F, per-kelvin and mm/m·K — instantly and with exact factors. Type a value, pick the units, and read the answer as you type.
Because a Celsius degree is 1.8 times a Fahrenheit degree, a µm/m·°C value is larger than the same coefficient in in/in·°F by 1.8. For the temperature scales, see the Celsius to Fahrenheit converter.
The units it covers
Every unit is a thermal expansion coefficient, so each converts through the per-kelvin with a fixed ratio.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| µm/m·°C (ppm/°C) | µm/m·°C | 1e-6 | Metric materials data |
| in/in·°F (ppm/°F) | in/in·°F | 1.8e-6 | US materials data |
| Per kelvin | 1/K | 1 | SI base (raw coefficient) |
| mm/m·K | mm/m·K | 1e-3 | Larger metric strain |
The formula
Each unit has a fixed value in per-kelvin, so any conversion goes through it once:
result = value × factor_from ÷ factor_toWhere:
- value = the number you typed, in the “from” unit
- factor_from = the “from” unit’s value in 1/K
- factor_to = the “to” unit’s value in 1/K
Worked example
Convert steel’s 12 µm/m·°C to in/in·°F.
1 in/in·°F = 1.8 µm/m·°C12 ÷ 1.8 = 6.667 µin/in·°FSo steel’s 12 µm/m·°C is about 6.67 µin/in·°F.
The units in this example
The metric coefficient of linear thermal expansion — micrometres of growth per metre per degree Celsius. Numerically the same as ppm/°C.
- steel ≈ 12 µm/m·°C
- aluminium ≈ 23 µm/m·°C
- 1 µm/m·°C ≈ 0.556 µin/in·°F
- 1 µm/m·°C = 1e-6 /K
The US coefficient — inches of growth per inch per degree Fahrenheit. Smaller than the °C form because the Fahrenheit degree is smaller.
- steel ≈ 6.7 µin/in·°F
- 1 in/in·°F = 1.8 µm/m·°C
- 1 in/in·°F = 1.8e-6 /K
- aluminium ≈ 12.8 µin/in·°F