What is crop factor in photography?

Crop factor is a number that describes the size difference between a camera's image sensor and a standard 35mm full-frame sensor (36mm × 24mm). When a sensor is smaller than full-frame, it captures a narrower field of view from the same lens, effectively "cropping" the image—hence the name crop factor.

For example, an APS-C sensor with a 1.5× crop factor captures an image that appears 1.5 times more "zoomed in" compared to the same lens on a full-frame camera. This directly affects the effective focal length: a 50mm lens on a 1.5× crop sensor produces a field of view equivalent to a 75mm lens on full-frame.

Understanding crop factor is essential when comparing lenses across different camera systems, planning equipment purchases, or achieving a specific field of view for your photography style.

Tool description

This calculator determines the crop factor for any camera sensor size by comparing it to the full-frame 35mm standard. It supports 15+ common sensor presets including full-frame, APS-C (Canon, Nikon, Sony, Fujifilm), Micro Four Thirds, medium format, 1-inch sensors, and smartphone sensors. You can also enter custom sensor dimensions for any camera.

Beyond crop factor, the tool calculates the 35mm equivalent focal length, sensor diagonal, aspect ratio, sensor area, and area ratio compared to full-frame—providing a complete picture of how your sensor size affects image capture.

Examples

Sensor Type Dimensions Crop Factor 50mm Equivalent
Full Frame 36 × 24 mm 1.0× 50mm
APS-C (Canon) 22.3 × 14.9 mm 1.6× 80mm
APS-C (Nikon/Sony) 23.5 × 15.6 mm 1.5× 75mm
Micro Four Thirds 17.3 × 13 mm 2.0× 100mm
1" Sensor 13.2 × 8.8 mm 2.7× 135mm
1/2.3" Sensor 6.17 × 4.55 mm 5.6× 280mm

Features

  • 15+ sensor presets: Full-frame, APS-H, APS-C (Canon, Nikon, Sony, Fujifilm), Micro Four Thirds, medium format, 1-inch, and smartphone sensors
  • Custom sensor input: Enter any sensor width and height in millimeters for specialized or vintage cameras
  • Focal length converter: Calculate the 35mm equivalent focal length for any lens
  • Complete sensor metrics: View diagonal length, aspect ratio, sensor area, and area comparison to full-frame
  • Auto-detection: Recognizes common aspect ratios (3:2, 4:3, 16:9, 1:1)

How it works

Crop factor is calculated by dividing the diagonal of a full-frame sensor by the diagonal of your camera's sensor:

Crop Factor = Full-Frame Diagonal ÷ Sensor Diagonal

The full-frame diagonal is approximately 43.27mm (calculated from √(36² + 24²)). For equivalent focal length, simply multiply the actual focal length by the crop factor:

Equivalent Focal Length = Actual Focal Length × Crop Factor

Supported sensors

Category Sensors
Full Frame 35mm (36 × 24 mm)
APS APS-H Canon, APS-C Canon, APS-C Nikon/Sony/Pentax, APS-C Fujifilm
Mirrorless Micro Four Thirds
Compact 1" (One Inch), 1/1.7", 1/2.3", 1/2.5"
Medium Format Fujifilm GFX, Hasselblad, 645 Format
Smartphone 1/1.3" (Large), 1/1.56" (Medium)

Use cases

  • Lens shopping: Determine the actual field of view you'll get when using full-frame lenses on crop sensor cameras, helping you choose the right focal length
  • System comparison: Compare the effective reach of your gear across different camera systems—useful when switching brands or adding a second body
  • Video production: Calculate equivalent focal lengths for cinema cameras with various sensor sizes to match shots across different camera setups

FAQ

Why do crop sensors make lenses appear longer? A smaller sensor captures only the center portion of the image circle projected by the lens. This narrower field of view mimics the effect of using a longer focal length on a full-frame camera, though the actual lens optics remain unchanged.

Does crop factor affect depth of field? Indirectly, yes. To achieve the same field of view on a crop sensor, you'd stand further back or use a wider lens—both of which increase depth of field compared to the same framing on full-frame.

Is a higher crop factor better for wildlife or sports? A higher crop factor gives you more "reach" from the same lens, which can be advantageous for distant subjects. However, smaller sensors typically have lower light sensitivity and dynamic range.