Observed dependence of FWHM on filament distance and observational resolution. Left: FWHM from asymmetric fits plotted against the distance of the field of each q = 1–2 profile (squares and crosses, respectively). For readability, the distance values include small added jitter. Median of each distribution is plotted with a solid line (q = 1) and dashed line (q = 2). Grey lines show the proposed relation of FWHM = 4 × HPBW (Panopoulou et al. 2022), as well as the Herschel (solid line) and ArTéMiS (dashed line) beamsizes. Right: Median value of each q = 1–2 dataset as a function of observational resolution in pc (solid squares). The errorbars represent the standard deviation of the FWHM widths in each dataset. Grey lines show relations of FWHM = [1,2,4] × HPBW. In both frames, we also include values from the literature (see text for references): Herschel continuum (yellow triangles), other continuum (orange diamonds), mean deconvolved filament widths from Fig. 1 of Panopoulou et al. (2022) (yellow circles), and values from Juvela & Mannfors (2023) with solid plusses (LR and HR in yellow, AR with orange, and MIR with red). The errorbars represent either the published uncertainty or a 30% uncertainty on the FWHM. In the left frame only, we show additional literature values from CO (purple stars) and NH₃ (purple hexagon) observations. Solid symbols represents deconvolved widths, those without beam deconvolution are shown with outlines.