A dynamic radiation monitor having a detector coupled to a computer to determine at any given location, the amount of time a person has before a pre-selected maximum permissible radiation exposure is received. The device dynamically calculates and outputs the user's permissible stay time for a given area based on a personalized maximum permissible dose, and adjusts in real time the output based on elapsed time and changing exposure rate. The device also provides the user audio and visual feedback such as varying background colors for different stay time ranges.