Conversion method
This converts coefficients per temperature interval. Linear and volumetric expansion coefficients must be compared like for like; their relationship depends on the material model.
°F⁻¹ = x × 0.5555555555555556
10 K⁻¹ = 5.555556 °F⁻¹.
| K⁻¹ | °F⁻¹ |
|---|---|
| 1 | 0.555556 |
| 5 | 2.777778 |
| 10 | 5.555556 |
| 25 | 13.888889 |
| 50 | 27.777778 |
| 100 | 55.555556 |
Unit definitions and sources
This converts coefficients per temperature interval. Linear and volumetric expansion coefficients must be compared like for like; their relationship depends on the material model.
| Unit and system | Use | Definition | Relationship |
|---|---|---|---|
| Per kelvin (K⁻¹); si | Common units | Per kelvin: base (per-k) = value × 1. Common use: Thermal Expansion. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Per Fahrenheit interval (°F⁻¹); si | Common units | Per Fahrenheit interval: base (per-k) = value × 1.8. Common use: Thermal Expansion. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Per Celsius interval (°C⁻¹); si | Specialist units | Per Celsius interval: base (per-k) = value × 1. Common use: Thermal Expansion. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Micrometer per meter kelvin (µm/(m·K)); si | Specialist units | Micrometer per meter kelvin: base (per-k) = value × 1e-06. Common use: Thermal Expansion. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Parts per million per kelvin (ppm/K); si | Specialist units | Parts per million per kelvin: base (per-k) = value × 1e-06. Common use: Thermal Expansion. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
Sources: NIST: SP 811 Appendix B.8: conversion factors; BIPM: SI prefixes
Precision of thermal expansion conversions
All 5 thermal expansion units convert through Per kelvin (K⁻¹). 5 have an exact defined relationship to the base unit and 0 are conventional or measured values. Results and the tables on this page come from the same engine, so a table value can be checked against the converter directly.
Standard display shows up to six decimal places, switching to scientific notation for very large or small values. Calculation uses JavaScript binary floating point independently of display rounding, so extra digits are not a claim about measurement accuracy. Each unit lists its own source; a citation records where the definition comes from, not an independent review. See Conversion methodology for the review and correction process.