Calculate camera crop factor, equivalent focal length, and effective aperture for any sensor size. Compare APS-C, Micro 4/3, full-frame and more.
Crop factor is the ratio of a 35mm full-frame sensor diagonal to your camera's sensor diagonal. It determines how a lens's focal length, field of view, and effective depth of field translate between different sensor sizes. Understanding crop factor is essential for comparing lenses across camera systems and predicting how a lens will perform on your specific body.
An APS-C sensor with a 1.5x crop factor makes a 50mm lens behave like a 75mm on full-frame in terms of field of view. But crop factor also affects the effective aperture for depth-of-field calculations—an f/1.8 lens on APS-C gives roughly the same depth of field as f/2.7 on full-frame.
This calculator computes crop factor from sensor dimensions, derives equivalent focal lengths, effective aperture, and equivalent ISO for noise comparison. It supports all common formats and lets you enter custom sensor dimensions for specialized or vintage cameras. The comparison table shows how the same lens performs across multiple sensor sizes, making it invaluable for photographers who work with multiple camera systems or are considering switching formats.
Whether you're deciding between an APS-C and full-frame body, evaluating a Micro Four Thirds kit, or calculating the reach advantage of a smaller sensor for wildlife photography, this tool gives you precise equivalence numbers.
Crop factor calculations are essential when buying lenses, comparing camera systems, or matching the look of one format on another. This calculator eliminates confusion by providing precise equivalences for focal length, depth of field, and noise performance. This tool is designed for quick, accurate results without manual computation. Whether you are a student working through coursework, a professional verifying a result, or an educator preparing examples, accurate answers are always just a few keystrokes away.
Crop Factor = diagonal_35mm / diagonal_sensor = 43.27mm / sqrt(w² + h²). Equivalent Focal Length = actual_FL × crop_factor. Effective Aperture (DOF) = f_stop × crop_factor. Equivalent ISO = ISO × crop_factor².
Result: 1.53× crop, 53.6mm equiv.
A Nikon APS-C sensor has a 1.53× crop factor. A 35mm f/1.8 at ISO 800 gives equivalent field of view of 53.6mm, equivalent DOF of f/2.8, and equivalent noise of ISO 1870 compared to full-frame.
The 35mm full-frame standard (36×24mm) was established by Oskar Barnack's Leica in the 1920s. When digital sensors arrived in smaller sizes, the "crop factor" became the standard way to express how optics translate between formats. The diagonal of a 35mm frame is approximately 43.27mm, and dividing this by your sensor's diagonal gives the crop factor.
The implications ripple through every aspect of photography: field of view narrows by the crop factor, depth of field deepens as if you had a smaller aperture, and total light gathered decreases proportional to the sensor area ratio (crop factor squared).
Medium Format (44×33mm) has a crop factor of about 0.79×. Full Frame (36×24mm) is the reference at 1.0×. APS-H (27.9×18.6mm) used in some Canon pro bodies is 1.3×. APS-C varies by manufacturer: 1.5× for Nikon/Sony/Fuji, 1.6× for Canon. Micro Four Thirds is 2.0×. One-inch sensors are 2.7×. Smartphones range from 5× to 8×.
When choosing between camera systems, crop factor equivalence removes the marketing haze. A Micro 4/3 camera with a 25mm f/1.4 lens gives equivalent results to a full-frame camera with a 50mm f/2.8—similar framing and depth of field. The full-frame system will have about 2 stops better noise performance (equivalent ISO is 4× higher on M4/3). Understanding these tradeoffs helps you choose the right system for your priorities: size/weight, image quality, lens availability, and budget.
Crop factor itself doesn't, but smaller sensors generally have smaller pixels (at the same megapixel count), which can affect noise performance and dynamic range. Understanding this concept helps you apply the calculator correctly and interpret the results with confidence.
No. The focal length is a physical property of the lens. Crop factor only describes how the field of view changes when the sensor captures a smaller portion of the image circle.
Most smartphone sensors have crop factors between 5x and 8x due to their very small sensors (typically 1/2.3-inch or smaller).
The crop factor gives extra "reach"—a 400mm lens on a 1.5x crop body frames like a 600mm on full-frame, which is advantageous for distant subjects.
Yes. For equivalent framing, a crop sensor produces less background blur. To match full-frame bokeh, you need to divide your aperture by the crop factor.
Medium format sensors are larger than full-frame, so they have a crop factor less than 1 (typically 0.79x for 44×33mm or 0.64x for Fuji GFX's 44×33mm system).