The aim of this study was to describe packing density of corn (n = 177) and winter forage (n = 73) silage structures on 99 California dairies. Dairies were visited at least once from 2010 to 2016. To determine density, silage structures were probed at 3 different face locations (right, middle and left) at 1.8 m from the bottom surface. Cut length was evaluated with a measuring tape. Silage samples were composited and a sample was sent to a commercial lab for dry matter (DM) determination. The overall density for each of the silage structures was calculated as an average of the 3 samples collected. Descriptive statistics, including first (Q₁), second (Q₂) and third (Q₃) quartiles as well as means, range and coefficient of variation (CV) were computed with the UNIVARIATE procedure of SAS. Means comparisons were performed with TTEST procedure of SAS. Corn silage structures were conventional piles (n = 118), bunkers (n = 6), bags (n = 10), rollover piles (n = 36), or hybrid piles (n = 7). Winter forage silage structures were conventional piles (n = 45), rollover piles (n = 18), bags (n = 8) or hybrid piles (n = 2). Average cut length was 1.7 cm (range: 1.3 to 2.2 cm) for corn silage and 1.6 cm (range: 1.3 to 1.9 cm) for winter forage. Corn silage DM was 34% (range: 28 to 45% of DM), while winter forage was 32% (range: 27 to 45% of DM). Corn silage structures had a higher (P < 0.01) packing density at the bottom-middle (269 kg of DM/m³) than at the bottom-right (247 kg of DM/m³) or bottom-left (239 kg of DM/m³). Average packing density was 223 (Q₁), 251 (Q₂) and 280 (Q₃) kg of DM/m³ for corn silage. In winter silage structures, higher (P < 0.01) packing density was observed at the bottom-middle (184 kg of DM/m³) than at the bottom-right (160 kg of DM/m³) or bottom-left (160 kg of DM/m³). Average packing density for winter forage was 135 (Q₁), 168 (Q₂), and 205 (Q₃) kg of DM/m³. In the bottom-middle sample location,75% of corn silage structures were above 240 kg of DM/m³, whereas 50% of winter forage structures were below 183 kg of DM/m³. Bagged silage was below recommended minimum packing densities for both corn and winter forage. California silage structure density can be improved, especially in winter forage structures.