Margin over concentrates (MoC) was identified as a practical indicator of management performance at dairy farms. It was found to be a more objective metric than income over feed costs (IOFC), yet it has been scarcely used in dairy farm management literature. Estonian University of Life Sciences and partner farmers conducted a study recording data on production processes in 10 midsize (190–750 milking cows) Estonian dairy farms on a monthly basis in 2012–2014. The study included detailed information on feeding and milk output. One of the key objectives of the study was to find reliable performance indicators that would assist dairy farmers in diagnosing and measuring potential weaknesses in farms’ production processes. In the study, MoC was calculated as milk sales turnover less cost of concentrate feeds for the milking herd (including dry cows, but excluding youngstock). Concentrate feeds included all feeds except grass, silages (grass and corn), hay and straw. Concentrate feeds were determined the biggest single cost component at the farms (29% of all dairy-related costs on average) and its efficient use has a significant effect on total farm profitability. MoC was found to effectively summarize the financial result of several other metrics, such as milk yield, milk price, percentage of discarded milk, and so on. MoC excludes cost of forage feeds that often lack reliable market price and can have very different physical and nutritional characteristics based of preparation timing, plant material and technology. Dairy farmers could benefit from using MoC as a broad measurement tool for the milk herd performance.