Photo Calculator is a simple cross platform software for measuring the depth of field in an image.
Depth of field is the distance between the nearest and furthest parts of an image. Photo Calculator allows you to avoid what the developer calls "the circle of confusion" by selecting the exact resolution you want from a list and Photo Calculator works it out for you.
Once open, Photo Calculator simply requires you to configure the coordinates you require including Film Format, Units and Resolution and the results will be presented the moment you click "OK". There are no preferences or options however and you can't change the fixed default aperture setting of f9.
Photo Calculator is a very simple program that's low on aesthetics but high on functionality for photographers that need to measure depths of fields.