Thermal Expansion Converter
Convert coefficients of thermal expansion between per kelvin (1/K), per degree Fahrenheit (1/°F), ppm/K and ppm/°F.
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Result
Thermal Expansion units
Every unit below converts to every other one in the calculator. Values are relative to the base unit, the per kelvin (1/K).
| Unit | Symbol | System | Value |
|---|---|---|---|
| Per kelvin | 1/K | SI | Base unit |
| Per degree Celsius | 1/°C | SI | = 1 1/K |
| Per degree Fahrenheit | 1/°F | US customary | = 1.8 1/K |
| Part per million per kelvin | ppm/K | SI | = 0.000001 1/K |
| Part per million per degree Fahrenheit | ppm/°F | US customary | = 0.0000018 1/K |
Per kelvin quick reference
| Per kelvin | Part per million per kelvin | Part per million per degree Fahrenheit |
|---|---|---|
| 1 1/K | = 1000000 ppm/K | ≈ 555555.5556 ppm/°F |
| 10 1/K | = 10000000 ppm/K | ≈ 5555555.556 ppm/°F |
| 100 1/K | = 100000000 ppm/K | ≈ 55555555.56 ppm/°F |
| 1000 1/K | = 1000000000 ppm/K | ≈ 555555555.6 ppm/°F |
Among the 5 thermal expansion units on this page, the smallest is the part per million per kelvin (ppm/K) and the largest is the per degree fahrenheit (1/°F).
More thermal expansion conversions
About thermal expansion units
The coefficient of thermal expansion tells how much a material grows for each degree of temperature rise, as a fraction of its size. Its SI unit is the reciprocal kelvin (1/K). Values are tiny, so they are usually written in ppm/K (10⁻⁶/K), which is the same as µm/(m·K).
A degree Fahrenheit is smaller than a kelvin, so the same material has a smaller number per °F: 1 ppm/°F is exactly 1.8 ppm/K, and 1 ppm/K is about 0.5556 ppm/°F. Per °C and per K are identical.
Frequently asked questions
- How do I convert ppm/°F to ppm/K?
- Multiply by 1.8. For example, 6.5 ppm/°F is 11.7 ppm/K. To go from ppm/K to ppm/°F, divide by 1.8.
- How do I calculate how much a part expands?
- Multiply length × coefficient × temperature change. Steel expands roughly 12 ppm/K, so a 10 m steel bar heated by 30 K grows by about 10 × 0.000012 × 30 = 0.0036 m, or 3.6 mm.
- Is 1/°C the same as 1/K?
- Yes. A degree Celsius and a kelvin are the same size, so a coefficient has the same value in both units.
- How many parts per million per kelvin are in one reciprocal kelvin?
- One reciprocal kelvin = 1000000 ppm/K (parts per million per kelvin).
- How many parts per million per degree Fahrenheit are in one reciprocal kelvin?
- One reciprocal kelvin ≈ 555555.5556 ppm/°F (parts per million per degree Fahrenheit).