We use a new self-consistent model to derive the conversion efficiency from rotation power to γ-ray power for pulsars (ηth). Our result indicates that ηth; ∝τ6/7P2, where τ and P are the characteristic age and period of the pulsar, which shows that although the efficiency increases with the characteristic age of the pulsar, it also depends on the pulsar period. We test our model results with the survey of high-energy γ-rays from pulsars by EGRET. Our model not only successfully explains the efficiency of the confirmed γ-ray pulsars but also explains why the γ-ray efficiency of millisecond pulsars is so low.