Sensor Crop Factor Calculator
Determine the magnification ratio between two camera sensors.
Full Frame (35mm) sensor diagonal is typically $43.3 \text{mm}$.
Example: Micro Four Thirds is $\approx 21.6 \text{mm}$.
Calculated Crop Factor
Magnification relative to Reference Sensor
1.52x
How many times smaller
1.3 Stops Difference
Please ensure both diagonal values are positive.
Understanding the Sensor Crop Factor
The Crop Factor (CF) is a fundamental concept in digital photography. It is simply the ratio that compares the size of a camera's image sensor to the size of a standard 35mm film frame, which is now referred to as a Full Frame sensor.
1. The Full Frame Reference
The 35mm Full Frame sensor is the universal standard in photography, defined by its image area of approximately 36×24mm, giving it a diagonal measurement of approximately 43.3mm.
A Full Frame sensor is assigned a Crop Factor of 1.0x. Every other sensor size is compared against this 1.0x reference.
2. How the Crop Factor is Calculated
The crop factor is calculated using the ratio of the sensor diagonals:
Crop Factor=Current Sensor DiagonalReference Sensor Diagonal
Example: A standard APS-C sensor has a diagonal of roughly 28.4mm.
Crop Factor=28.4mm43.3mm≈1.52
This is why many APS-C cameras (like Nikon, Sony, and Fuji) are said to have a 1.5x crop factor.
3. Why the Crop Factor Matters
The crop factor has two major implications for your photography: Field of View and Light Gathering.
A. Field of View (Focal Length Equivalence)
When you mount a lens on a cropped sensor camera, the sensor "crops" the image circle projected by the lens, making the scene appear more magnified than it would on a Full Frame camera.
To find the equivalent field of view:
Full Frame Equivalent FL=Actual Focal Length×Crop Factor
If you use a 50mm lens on a 1.5x crop camera, the resulting image will have the same field of view as using a 75mm lens on a Full Frame camera.
B. Light Gathering and Depth of Field (Stops Difference)
The calculator also displays the difference in light gathering (or sensor area) in Stops.
The area ratio between the two sensors is the Crop Factor2. Since the amount of light gathered is proportional to the sensor area, this ratio tells you the difference in depth of field and the amount of noise-free light gathered (assuming the same f/stop and shutter speed):
Stops Difference=log2(Crop Factor2)
For a 1.5x crop sensor, the area ratio is 1.5×1.5=2.25. This means the APS-C sensor has about 2.25 times less area than Full Frame, which equates to about 1.17 stops less light gathering potential, which in turn affects your depth of field compared to Full Frame at the same physical aperture.