Valid and reliable methods for measuring plate waste are essential to improving foodservice efficiency and patient nutrition management. Although direct weighing is considered the most accurate method for quantifying food waste, it is often impractical in clinical settings due to labour and time constraints (1). Alternative methods such as visual estimation, particularly digital photography, may offer a feasible solution. This study examined the accuracy of a digital photography method for quantifying whole plate waste (aggregate) in an acute care hospital setting. Plate waste data were collected across three main meals over seven breakfasts, 21 lunches, and 21 dinners. Each plate was photographed before and after consumption, and leftover food was weighed using an electronic scale. A total of 1763 plates (n = 108 for breakfast; n = 804 for lunch; n = 851 for dinner) were assessed using both direct weighing and digital photography with a 7-point visual scale (0%, 10%, 25%, 50%, 75%, 90%, 100% of food remaining). A subsample of 200 plate images (n = 20 for breakfast; n = 90 for lunch; n = 90 for dinner) was independently evaluated by two assessors to determine inter-rater reliability. Waste per food component was calculated as: the visually estimated proportion (%) of food remaining × the recommended standard serving size of each menu item (2). Spearman correlation coefficients assessed associations between the two methods, and the Bland-Altman analysis evaluated agreement (3). A strong positive correlation was observed between the two methods (rs = 0.9895, p < 0.001), with consistent results across meals (breakfast: rs = 0.9950, p < 0.001; lunch: rs= 0.9882, p < 0.001; dinner: rs = 0.9882, p < 0.001). Bland-Altman analysis indicated good agreement, with a mean difference of 4.67 g and 95% limits of agreement ranging from -50.51 to 59.84 g. Mean differences were consistent across meals (breakfast: -5.22 g; lunch: 5.05 g; dinner: 5.56 g), with breakfast showing narrower limits of agreement than lunch and dinner (breakfast: -33.96 to 23.51 g; lunch: -50.99 to 61.09 g; dinner: -50.91 to 62.02 g), likely due to simpler meal composition. Inter-rater reliability was high [ICC range: 0.874 (95% CI: 0.815-0.916) to 0.972 (95% CI: 0.958-0.982)], indicating good consistency between assessors. Findings support digital photography as a valid method for quantifying whole plate waste in acute care hospital settings. It also highlights the utility of digital photography in monitoring plate waste over time, informing food waste reduction strategies, and evaluating the effectiveness of interventions to enhance patient satisfaction and improve nutritional intake.