The objective was to determine effects of converting calves from a component-fed ration to a TMR at 8, 10, or 12 wk of age on intake, growth, and nutrient digestibility. Holstein calves (n = 40) were randomly assigned to 1 of 4 groups (no TMR, TMR conversion at 8, 10 or 12 wk; T0, T8, T10, and T12 respectively). Calves were weaned at 6 wk of age, housed individually, and studied from 7 to 14 wk of age. Rations, consisting of a 20% crude protein texturized starter and grass hay, were offered ad libitum as separate components or as a TMR with 85% starter and 15% grass hay on a DM basis. Intake and BW were measured weekly. Component intake for TMR was calculated from the proportion of each in the TMR. Fecal grab samples were collected and composited every 9 h over 3 d at 9, 11, and 13 wk of age from the same 4 calves per group. Feed and feces were evaluated for DM, NDF, ADF, and ADL (internal flow marker) to estimate digestibility. The statistical model included group (fixed), calf (random), and age (repeated). The slice option was used to determine effects of diet and age on digestibility of nutrients. Initial BW and hip width were used as covariates to evaluate DM intake and growth. Intake did not vary between groups (P > 0.1). However, at all ages calves fed TMR ate more hay and less starter than component-fed calves (P < 0.05). Average daily gain did not vary between groups (P > 0.1), but empty BW gain tended to be lower for calves put on TMR earlier (T0 = 1.08, T8 = 0.94, T10 = 1.04, and T12 = 1.06 kg/d P = 0.07). Hip growth was less for calves fed TMR earlier (T0 = 0.90, T8 = 0.80, T10 = 0.85, and T12 = 0.88 cm/wk P < 0.05). Digestibility of DM was greater at 9 wk for T8 vs. others (P < 0.05). Fiber digestibility was greater for calves on TMR at 9, 11, and 13 wk of age (P < 0.01 at all ages). We conclude that increased fiber digestibility allowed weaned calves on a TMR to consume less concentrate without affecting weight gain compared with component-fed calves during this study.