Famine scales are the ways in which degrees of food security are measured, from situations in which an entire population has adequate food to full-scale famine. The word "famine" has highly emotive and political connotations and there has been extensive discussion among international relief agencies offering food aid as to its exact definition. For example, in 1998, although a full-scale famine had developed in southern Sudan, a disproportionate amount of donor food resources went to the Kosovo War. This ambiguity about whether or not a famine is occurring, and the lack of commonly agreed upon criteria by which to differentiate food insecurity has prompted renewed interest in offering precise definitions. As different levels of food insecurity demand different types of response, there have been various methods of famine measurement proposed to help agencies determine the appropriate response.
A tension that has existed in all attempts to define a famine is between definitions of famine as an event and definitions as a process. In the first case, famine is defined (roughly) as the event of many people dying of starvation within a locality or region. In the second, famine is described as a chronology beginning with a disruption or disruptions that gradually leads to widespread death. However, these general definitions have little utility for those implementing food relief as "region", "widespread", etc. are undefined.
One of the earliest methods of measurement was the Indian Famine Codes developed by the colonial British in the 1880s. The Famine Codes defined three levels of food insecurity: near-scarcity, scarcity, and famine. "Scarcity" was defined as three successive years of crop failure, crop yields of one-third or one-half normal, and large populations in distress. "Famine" further included a rise in food prices above 140% of "normal", the movement of people in search of food, and widespread mortality. The Punjab Food Code stated, "Imminence of death is the sole criterion for declaration of famine." Inherent in the Famine Codes was the assumption that famine was an event, and not a process.
The basic premise of the Famine Codes formed the basis of numerous subsequent early warning systems. One of the most efficacious is the Turkana District Early Warning System in northern Kenya in which indicators include rainfall levels, market prices of cereals, status of , rangeland conditions and trends, and enrollment on food-for-work projects. The system identifies three levels of crisis: alarm, alert and emergency, each of which is linked to a planned response to mitigate the crisis and try to prevent a worsening of the situation.