An equation for predicting the strength of wood beams with end notches on the tension side (Tension-side End Notches or TEN) was derived using a critical fillet hoop stress (CFHS) theory. The equation combines the results of finite element and statistical analyses of 690 different TEN beam configurations and experimental tests of 362 full-size beams. It accounts for the effects of loading type, end support and beam and notch geometry variables such as beam height, fractional notch depth, radius, and notch location. The effect of span-to-depth ratio is implicit to the model. Notched beam strength is represented by a material parameter, k, which can be obtained from notched beam tests. The equation is applicable to both filleted and sharp-cornered notches. An effective radius, Re, which models the effect of a sharp-cornered notch, was determined and confirmed for two wood materials. A method of determining Rc for other materials was established. The results of this study can be used to set new design criteria for the strength of notched wood beams
