Crop Factor Calculator
Calculate the equivalent focal length of a lens on a crop-sensor camera compared to full-frame. Use this when comparing lenses across different camera systems or predicting field of view.
About this calculator
Crop factor (also called the focal length multiplier) describes the ratio between the diagonal of a full-frame 35 mm sensor (43.3 mm) and the diagonal of a smaller sensor. Because a smaller sensor captures only the central portion of the lens's image circle, it effectively narrows the field of view, as if you had used a longer focal length lens on full frame. The equivalent focal length is: Equivalent Focal Length = actualFocalLength × cropFactor. Common crop factors are 1.5× for APS-C sensors (Nikon, Sony, Fuji), 1.6× for Canon APS-C, and 2× for Micro Four Thirds. A 50 mm lens on a camera with a 1.5× crop factor behaves like a 75 mm lens on a full-frame body in terms of field of view. Depth of field and lens optics are unchanged; only the framing is affected.
How to use
You own a 35 mm f/1.8 prime lens and a Sony APS-C camera with a crop factor of 1.5×. Step 1: Enter actual focal length — 35 mm. Step 2: Enter crop factor — 1.5. Step 3: Calculate — 35 × 1.5 = 52.5 mm equivalent. Your lens will frame shots similarly to a 52.5 mm lens on a full-frame camera — essentially a 'nifty fifty' field of view. This makes it a versatile walk-around lens on that body.
Frequently asked questions
What is the crop factor of common camera sensors and how is it calculated?
Crop factor is calculated by dividing the diagonal of a full-frame 35 mm sensor (43.3 mm) by the diagonal of the smaller sensor in question. Canon APS-C sensors have a crop factor of approximately 1.6×, Nikon and Sony APS-C sensors are 1.5×, and Micro Four Thirds cameras (Olympus, Panasonic) use a 2× crop factor. Medium format cameras have a crop factor below 1 — their sensors are larger than 35 mm, so lenses behave as if they have a shorter focal length relative to full frame.
Does crop factor affect depth of field as well as field of view?
Crop factor affects field of view directly, but depth of field only changes if you are comparing equivalent framing — that is, if you adjust your shooting distance to match the full-frame composition. If you stand in the same spot, depth of field from the lens itself does not change because aperture and subject distance are the same. However, to recreate the same framing on a crop sensor as a full-frame shot, you must either move farther away or use a wider lens, both of which increase depth of field. This is why full-frame cameras are often preferred for shallow depth-of-field portraits.
Why does crop factor matter when buying lenses for a mirrorless or DSLR camera?
Understanding crop factor helps you predict how a lens will behave on your specific body before you buy it. A 200 mm telephoto becomes a 320 mm equivalent on a 1.6× crop sensor — great for wildlife and sports shooters who want extra reach. Conversely, wide-angle lenses become less wide: a 24 mm lens becomes a 36 mm equivalent, which may not satisfy architectural or landscape photographers seeking dramatic wide perspectives. Many manufacturers offer lenses specifically designed for crop-sensor cameras, which are lighter and cheaper, but these lenses cannot be used at full resolution if you later upgrade to a full-frame body.