Diameter of the largest limb in the breast height region (DLLBH) of trees is a good predictor of largest limb average diameter, a log knot index used in product recovery studies to predict product grade mix and value. DLLBH was measured on 2,252 Douglas-fir (Pseudostuga menziesii (Mirb.) Franco) trees from nine sites each with three plot pairs established at age 6 to 13 years. One of each pair was thinned, and the other was thinned and fertilized with 224 kg ha⁻¹ N as urea at establishment and every four years thereafter. DLLBH was measured at age 21 to 31 years when BH branches were dead. Fractional polynomials were used to develop models to predict DLLBH. One model (r_adj² = 0.69, root mean square error [RMSE] = 4.86) used only tree variables: diameter at breast height (DBH), total height, height to crown base, taper, and tree social position in the stand. A model that included treatment (if fertilized or not), stand density, and site index was a significant improvement (r_adj² = 0.72, RMSE = 4.62). The tree-variables-only model and the combined tree and stand variables model can be used with individual tree growth models to estimate the distribution of tree DLLBH in a stand for use with process capability analysis to assess conformance with external tree quality specifications. A model using variables measurable with light detection and ranging and knowledge of site index and treatment history was also developed (r_adj² = 0.56, RMSE = 5.78). This model suggests that there is an opportunity to use remote sensing to obtain and map (using a geographic information system) preharvest distributions of tree DLLBH in stands across a landscape for harvest scheduling and silvicultural planning.