To calculate the lifting capacity of a building hoist, you need to consider several factors. First, identify the hoist's rated capacity, which is usually specified by the manufacturer. This is the maximum weight the hoist is designed to lift. Next, assess the condition of the hoist, including any wear and tear that might affect its performance. Check the hoist's mechanical components, such as cables, pulleys, and motors, to ensure they are in good working order. Additionally, consider the weight of the load you intend to lift and any additional factors like the frequency of lifts or the height of the lift. Always operate within the hoist's rated capacity and follow safety guidelines to prevent accidents.