Lens Magnification and Depth of Field Calculator

Which of my lenses is best suited for macro photography? How much would a lens extension tube improve the situation? What depth of field can be expected?

Here is an easy to use calculator for these questions. Just enter the focal length of your lens, focusing distance and selected f-stop, and see what happens.

focal length mm
focusing distance m
extension tube mm
circle of confusion mm, or select
magnification x
effective focusing distance m with extension tube
near limit m
far limit m
angle of view ° diagonal
hyperfocal distance m
object diameter resolved mm for infinity focus
object distance mm
image distance mm

How does it work? Here's the theory behind it.