The focal length converter is a tool used to compare the equivalent focal length of lenses between various different film or CCD sensor sizes. Since the aspect ratio of each film type is potentially different four results are given; width, height, diagonal and the average of the results.

To use this simply enter a focal length in the first input box, select the format that this focal length is currently in, and then select the format that you wish to convert to. Press Convert and you have the result.

For example:
If you have a 80mm lens in a 6×6 medium format film system and you want to find out what lens this is equivalent to in a 35mm film system, enter 80mm as the focal length, 6×6 as the from format, and 35mm as the to format.

Press Convert to see the results.