There’s no formula to calculate overtourism. But there is one to solve it

There is a paradox at the heart of tourism. Often seen as a driver of economic and cultural growth, it also carries within it the seeds of its own decline. From the moment a destination opens to visitors, it begins to change, altered by the very presence of those it attracts. Over time, this gradual transformation can lead to overtourism, where the psychological carrying capacity of a location is exceeded, causing the destination to lose its appeal. Without a precise formula to measure this threshold, researchers have developed a tool, the “flow congruence index“, to assess the balance between tourist demand and a region’s ability to sustain it. This method helps highlight where imbalances could lead to the decline of once-thriving tourist spots. Tolerable impact before development In the early phases of Butler’s tourism life cycle model — exploration and involvement — tourism impact remains minimal as long as visitor traces are contained. However, the landscape soon started to change with the appearance of the first hotels and other infrastructure. Local residents begin to view tourism as a source of development, which shifts the existing social and economic order. Traditional livelihoods, culture, and customs become reshaped to meet the demands of visitors. Waste management also becomes a concern, as seen in the Maldives, where an entire atoll has been repurposed as a landfill. Such developments are unsustainable, clashing with the pristine conditions that initially fuelled tourism and economic growth in the region. Stagnation and decline At this point, despite appearances of limitless growth, the “virus” of tourism is already active. Butler argues that, after the stages of development and maturity, destinations enter stagnation. Growth halts, and visitors become disillusioned as they sense the degradation. Without corrective measures, destinations slip into decline, with tourism dwindling to marginal levels. When carrying capacity is breached J-M. Mïossec offers a more detailed account of the saturation phase that precedes decline: transport networks cover the entire region, and the local population focuses entirely on serving tourists. Visitors begin to recognise the changes and find that the destination no longer meets their expectations. This marks the point where the destination exceeds its carrying capacity—the point where the area can no longer sustain growth, and tourists are unwilling to tolerate overcrowding, deteriorating services, and overt commercialization of local customs. Limits of psychological carrying capacity There is no definitive formula for calculating the exact carrying capacity. It isn’t about the number of hotel beds, parking spaces, or access infrastructure. Rather, it’s a psychological threshold, beyond which the “tourism ecosystem” loses balance, and visitors no longer experience the same appeal as they did before. For instance, 1,000 tourists in Milan’s Piazza del Duomo might be acceptable — even desirable, given the urban setting. But 100 tourists on a mountain trail could feel overcrowded for those seeking peace and connection with nature. So overtourism can be defined as the excessive crowding that distorts a destination beyond its carrying capacity, leading to visitor rejection. Tourist redistribution Overtourism also has significant socioeconomic repercussions. It drives up prices, reduces housing availability, and forces residents to move away due to the high costs. The concentration of tourism in key destinations also marginalises other locations in the region, where attractions may exist but go unnoticed. A redistribution of tourist flows could help alleviate overtourism, minimise the underuse of facilities during the off-season, and improve visitor satisfaction by reducing overcrowding. The flow congruence index While it is impossible to mathematically define a destination’s carrying capacity, it is possible to