An image processing apparatus includes a hardware processor. The hardware processor estimates a body thickness and an irradiation field region of a subject based on a radiograph obtained by radiographing the subject. Further, the hardware processor calculates a distance from a focus of a radiation source to a radiation entrance point based on the body thickness. Still further, the hardware processor calculates an irradiation field size based on the irradiation field region. Yet further, the hardware processor calculates an exposure dose based on the distance, the irradiation field size, and in imaging condition used in radiographing the subject.
