When temperature changes, a solid’s dimensions change as well. This table reproduces selected linear expansion coefficients listed by NIST for a reference temperature of 295 K (about 22 °C). It is a small reference set for orientation, not a certified design-property table for every alloy or temperature range.

Selected linear thermal expansion values

Estimate a length change

For a constant coefficient over the temperature interval, the simple estimate is ΔL = α L₀ ΔT. Convert the listed coefficient from 10⁻⁶ K⁻¹ to K⁻¹ before using it. For example, a one-meter aluminum length and a 50 K increase give an estimated change of 22.91×10⁻⁶ × 1000 mm × 50 = 1.1455 mm.

A temperature interval expressed in degrees Celsius has the same numerical size as an interval in kelvins. The reference temperature still matters: a coefficient measured around room temperature may not represent the average coefficient across a wide interval.

Use the exact alloy and temperature range

Thermal expansion varies with composition, heat treatment, manufacturing condition, and temperature. “Aluminum” or “stainless steel” is not a complete material specification. The brass value in this table is explicitly for the listed 70% copper / 30% zinc composition, and the stainless entry is specifically grade 304. Other grades and tempers can differ.

For precision fits, long structures, thermal cycling, or temperatures far from 295 K, obtain temperature-dependent data for the exact material condition from the supplier or governing standard. Where the coefficient changes appreciably, calculate strain by integrating the coefficient across the interval or use an authoritative average expansion value for that range. Include the expansion of mating components and the constraints at supports.

What the table does not cover

These values do not predict stress caused by constrained expansion, thermal gradients, distortion, creep, phase changes, or joint behavior. A freely expanding part and a part restrained by a rigid assembly can experience very different forces even if their free length change is identical. Use a full thermal-mechanical analysis when loads, tolerances, safety, or service performance depend on it.

Source and data age

The listed values come from NIST’s NCNR sample-mounting reference tables, under “physical properties of selected metals at 295 K.” NIST attributes the table to Guy K. White’s 1979 low-temperature physics text and the 56th edition of the CRC Handbook (1975). Treat the values accordingly: useful as a traceable room-temperature reference, while current project work should use current supplier data for the specified material.