A tape-peeling model based on the geometry of the peel zone (PZ) is derived to predict the peeling behavior of adhesive tapes at peel angles less than or equal to 90 degrees. The PZ model adds an angle-dependent multiplier to the Kendall equation that takes into account the geometrical changes within the peel zone. The model is compared with experimental measurements of the peel force at different angles for a model tape and two commercial tapes, each with different bending moduli, stretch moduli, and adhesive strengths. Good agreement is found for a wide range of peel angles. The PZ model is also applied to the gecko adhesive system and predicts a spatula peel angle of 18.4 degrees to achieve the adhesion forces reported for single setae. The PZ model captures the fact that adhesive forces can be significantly enhanced by peeling at an angle, thereby exploiting high friction forces between the detaching material and the substrate.