The Resolve Optics FOV Calc will quickly enable you to work out the field of view, in centimetres and degrees, provided by a focal length at a known object distance or at infinity for the sensor format selected.

Sensor formats can be edited or added and stored, all you need to know is the horizontal and vertical dimensions of the sensor. This app has just launched on the app store and retails for $0.99/£0.69. You can download it here.