A series of 12-amino acid peptide analogs is designed using point mutation strategy based on an α-helical peptide template. The first mutation in the series, KL12, has an idealized facial amphiphilicity. Subsequent mutations are performed to increase hydrophobic or cationic contents. Idealized facial amphiphilicity show enhanced antimicrobial activity and selectivity against most of the tested microbes. Increasing hydrophobic contents further enhance antimicrobial potency; however, selectivity of the most hydrophobic analog is impaired due to non-specific interactions with mammalian cell membrane. This study demonstrates that facial amphiphilicity and hydrophobic content are strongly correlated with antimicrobial activity and selectivity of antimicrobial peptides.