Sensor Formats — FocalMath
Sensor format is the single input that changes more downstream photography math than anything else: it sets your crop factor, it sets the circle of confusion used in every depth-of-field and hyperfocal calculation, and it determines what a given focal length and aperture actually look like once light hits the sensor.
17 real, distinct formats are covered here — full frame, both common APS-C variants (Canon's 1.6x crop and the 1.5x crop used by Nikon, Sony and Fujifilm), Micro Four Thirds, several compact sensor sizes down to 1/2.3", two medium-format digital sizes, APS-H, Super 35 cine, large-format sheet film, and several medium-format and half-frame film formats. Every dimension listed is a real published spec, and every derived number — diagonal, crop factor relative to full frame, and circle of confusion using the diagonal/1500 convention — is computed from those real dimensions rather than looked up from a separate table, so a sensor page and the calculators can never quietly disagree.
If you're not sure which format your camera uses, the camera-body reference lists the sensor format for genuinely popular bodies across every major system.
How to Use These Pages
Each sensor page states four real numbers: the physical width and height in millimeters, the diagonal measurement derived from those, the crop factor relative to full frame, and the circle of confusion used in depth-of-field calculations. All four are computed from the same real dimensions the calculators use internally, so a sensor page and a calculator result can never quietly disagree with each other — there's exactly one table behind both.
Sensor formats span an enormous practical range: full frame and larger medium-format sensors sit at one end, genuinely large pieces of silicon (or, for the film formats, correspondingly large frames of film) that produce shallow depth of field and excellent low-light performance; compact 1/2.3" sensors used in many point-and-shoot cameras and consumer drones sit at the other end, trading those qualities for smaller, lighter, more affordable systems with substantially more forgiving depth of field at a given aperture. Understanding where your format sits on that spectrum explains a lot about why your camera behaves the way it does compared to a friend's different system, and several large-format and medium-format film sizes are included here too, for anyone shooting or researching film equipment alongside digital, all with the same real-dimension treatment as the digital formats, computed the same way and never rounded off for convenience.