Electronic nematicity in iron-based superconductors (FeSCs) couples bilinearly to orthorhombic strain, allowing nematic correlations to appear in the lattice response. Here we use neutron Larmor diffraction to measure the temperature-dependent distribution of relative d spacings in electron-doped Ba(Fe₁₋ₓCoₓ)₂As₂, hole-doped Ba_(0.83)K_(0.17)Fe₂As₂, FeSe, and Fe_(1.07)Te. In Ba(Fe₁₋ₓCoₓ)₂As₂ crystals without intentionally applied uniaxial stress, the in-plane distribution width, ε_(rm FWHM), increases on cooling in the tetragonal phase and can be described phenomenologically by a Curie–Weiss-like form. The fitted scale T^* decreases with Co doping and evolves similarly to the nematic phase diagram inferred from elastoresistance, although the two experiments probe different response functions. Related broadening in Ba_(0.83)K_(0.17)Fe₂As₂ and FeSe supports extending this interpretation beyond electron-doped BaFe₂As₂. By contrast, Fe_(1.07)Te shows no extended Curie–Weiss-like regime without applied stress, whereas uniaxial pressure produces a strongly anisotropic broadening that can contain contributions from both the field-biased lattice response and inhomogeneous loading. A mean-field model with bilinear nematoelastic coupling and spatially varying symmetry-breaking stress explains the Curie–Weiss-like broadening in terms of the renormalized orthorhombic compliance. Neutron Larmor diffraction therefore provides a bulk-sensitive probe of nematic-related lattice broadening that complements electronic and elastic measurements.