A method of distance estimation is to be implemented using a digital camera, and includes: selecting a pre-established reference dimension corresponding to a target whose distance is to be estimated; enabling operation of the digital camera to capture a clear image containing the target; obtaining a focal length corresponding to the captured clear image; calculating an image dimension for each of predetermined distance values with reference to the selected reference dimension and the focal length; and showing the distance values on a display unit at positions based on proportions of the calculated image dimensions. The distance of the target can be estimated as one of the distance values corresponding to a dimension of the target image contained in the clear image and shown on the display unit.