Investigations of past fires suggest that building occupants faced with a fire have problems defining the severity of it, especially in the early stages of the fire. An experiment was therefore carried out to study people’s ability to estimate fire growth, and their perceived ability to extinguish a fire using a portable fire extinguisher. A total of 535 persons, namely 304 men and 231 women, were asked to fill out a questionnaire that was divided into three parts. In the first part the test participants were asked to estimate the time between different stages of a fire. The second part involved estimations of the own ability to extinguish a fire with a portable fire extinguisher. The third part involved general questions about age, gender and academic background. The results suggest that people in general are not very good at defining the severity of a fire when it is visually accessible. Estimations of the fire growth did not correspond very well to the actual fire growth, and a great proportion of the test participants believed that they had not been able to extinguish an extinguishable fire using a portable fire extinguisher. It is therefore argued that the perceived risk not always conforms to the real risk in a fire situation where the fire is visually accessible. The results can be used to explain why building occupants not immediately initiate evacuation in a fire situation, even when the fire is visually accessible
