Depth of field calculator

End picture size and required pixel size
Seeing capabilities angle	Watching distance mm	Smallest detail needed mm
Width mm	Heigth mm	Aspect Ratio mm
Required width pixels	Required heigth pixels	Required dpi
Film plane parameters
Width mm	Heigth mm	Circle of confusion
Lens settings
Focal length mm 24 28 35 50 85 100 135 200 300 400 500	Focus distance m	Aperture 1.4 2 2.8 4 5.6 8 11 16 22 32
Object size m x m
Depth of field
Distance near sharp m	Distance far sharp m	Hyperfocal distance m
	Help text (press next to field to get the help text here)

Theory links (Link to parent category)

Digital Outback photo - "Image Sensor Size and Field of View" (good chart of common sensor sizes)
Digital Outback photo - "Pixel size"
Photo.net Effects of the physical size of digican sensors on performance by Bob Atkins
Focal length compression explained