Slice-GRAPPA (SG) is often used to reconstruct blipped-CAIPI simultaneous multi-slice EPI data, in particular in conjunction with the dual even-odd kernel approach (SG-DK) to mitigate ghosting related reconstruction artifacts. To achieve good performance in blipped-CAIPI acquisition, the CAIPI shift factor should be optimized in a case by case manner to minimize g-factor penalty. The g-factor is influenced by the reconstruction approach and so far a fast analytical g-factor calculation has been developed only for standard SG reconstruction but not SG-DK, where time-consuming Monte Carlo simulation is still needed. Here we propose an analytical g-factor calculation for SG-DK and demonstrate that the proposed method is fast and accurate. Our simulation and experimental results also highlight the superior performance of SG-DK over SG reconstruction, both in mitigating image artifacts and noise penalty.