Wavelength-dependent overestimation factors of disk sizes in the presence of a BLR component. The effect of the power-law index of the emissivity profile (Eq. (1)) is small within the range [ − 3, 0] (shaded regions). The inset shows the relative contribution of the BLR to the flux in the band, α, according to two models: the observationally motivated phenomenological line emission model of Vanden Berk et al. (2001) is shown in blue, and the more physical BLR model of Korista & Goad (2019) in red.