Site response in ground‐motion prediction equations (GMPEs) is primarily characterized as a function of the time‐averaged shear‐wave velocity over the top 30 m of the site profile (). Although the use of as a main site‐response predictor parameter is practical, GMPE site adjustments to different target regions or target site conditions require characterization of the GMPE’s rock‐site response in terms of host profile and host kappa. Regional profiles and kappa values have been traditionally used to characterize GMPEs host site conditions. These regional site properties may not reflect the average site response in GMPEs. We present a methodology, based on the quarter‐wavelength principles, that allows the derivation of GMPE‐compatible host 1D profiles and kappa values. This methodology is applied to the Next Generation Attenuation‐West2 (NGA‐West2) GMPEs to derive GMPE‐specific host profiles and kappa for western United States (WUS) site conditions with of 360, 490, 620, 760, and 1100 m/s. This application uses, for input, the GMPEs’ site response in Fourier amplitude spectra domain relative to a reference of 1000 m/s and requires an assigned profile for the reference site condition. The impact of the choice of reference profile on the results is not large. Comparisons of the derived GMPE‐specific profiles for of 760 m/s show differences in the host profiles among the NGA‐West2 GMPEs for the same site condition in WUS. Differences are also observed when comparing the derived GMPE‐compatible profiles with the commonly used profiles for WUS for of 760 m/s. These differences highlight the importance of using GMPE‐compatible profiles and kappa in GMPE adjustments and in site‐response analyses. Limitations of this approach for soft site conditions are discussed.