Comparison of various XUV estimation methods and observational data. Following Linsky et al. (2014), we divided the observable wavelength band into four bins and compared the flux in each bin, distinguished by symbols. Symbol colours correspond to different stars. Panel a shows the comparison between our model and the observation. Arrows indicate the correction to the model spectrum due to insufficient resolution. Panel b represents the comparison between the Lyman-alpha-based estimation (Linsky et al. 2014) and observation, while Panel c shows the comparison between the estimation based on surface magnetic flux (Namekata et al. 2023) and observation.