Food services generate significant amounts of food waste, which is originally edible and already prepared for eating, causing unnecessary impacts on the environment and the economy. Food waste studies have been conducted with varying methods and there are also large differences between food service subsectors and outlets. These challenges also make the data on food waste in the food service sector highly variable. We present a summary of three case studies from Finland with similar measurement methodologies. In these buffet type restaurants, we found serving waste to be the most significant source of food waste before kitchen waste and customer leftovers. For comparison and context, we also summarize the results of two additional cases from non-western countries. Measurement studies reveal food waste sources, which helps to plan interventions to reduce food waste. In the future, development of common indicators and easy to use weighing methods are necessary to improve both the quality and quantity of measurements.