Although food waste is known to have a negative impact on the environment, little research about the causes for food waste in school and kindergarten kitchens has been made. In order to identify factors with a significant influence on food waste in schools and kindergartens, divided into plate and serving waste, correlation analysis was performed on quantitative factors. Among the factors that were analyzed, children’s age (n=35, p<0.001, Kendall’s rank correlation tau=0.44), the number of semesters with food waste measurements (n=151, p<0.05, Kendall’s rank correlation tau=0.15) and portion size as an indicator for overproduction (n=97, p<0.01, Spearman’s rank correlation rho=0.28) were significantly increasing plate waste. Serving waste was significantly increased by portion size (n=97, p<0.0001, Spearman’s rank correlation rho=0.42) and was generally higher in satellite units than in production units (n=142, p<0.05, Pearson’s product-moment correlation r=0.19). Multiple linear regression models were developed to quantify the factors’ impact on plate, serving and total waste. While possible causes for serving waste should be further researched, the model for plate waste explained over 70 % of the variation in plate waste in schools and kindergartens. Due to the correlation between children’s age and plate waste, schools with students in higher grades could introduce more structured lunch breaks in order to reduce their plate waste. Furthermore, plate waste could be reduced if students are constantly aware of the food waste issue. Schools and kindergartens should also improve the grounds for the planning of their food production to reduce their portion sizes.