Focal Length Calculator — Full-Frame Equivalent & Field of View
Calculate the full-frame equivalent focal length and field of view for any lens and sensor combination. Supports APS-C, Micro Four Thirds, 1-inch, and phone sensors.
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Results
Full-Frame Equivalent
50mm
Crop factor: 1×
Field of View (Diagonal)
46.8°
Normal
Horizontal FOV
39.6°
Vertical FOV
27.0°
Sensor: 36×24mm · Crop 1×
Actual focal length: 50mm
Equivalent on FF: 50mm
Understanding Focal Length and Crop Factor
Focal length determines how "zoomed in" a photo appears. A shorter focal length gives a wider view; a longer focal length narrows the field of view and magnifies distant subjects. The same lens behaves differently on different sensor sizes due to the crop factor.
A 50mm lens on a full-frame camera gives a 47° diagonal field of view. The same lens on a Micro Four Thirds camera (2× crop factor) gives a 100mm full-frame equivalent — a 24° diagonal field of view, ideal for portraits.
Crop factor by sensor
- Full Frame (35mm): 1.0× — no crop
- APS-C (Canon): 1.6× crop
- APS-C (Nikon, Sony, Fuji): 1.5× crop
- Micro Four Thirds (Olympus, Panasonic): 2.0× crop
- 1-inch (Sony RX100, Nikon 1): 2.7× crop
Frequently Asked Questions
What is the full-frame equivalent focal length?
Full-frame equivalent focal length converts a lens's actual focal length on a crop sensor to the equivalent field of view on a full-frame (35mm) camera. A 50mm lens on an APS-C camera (1.5× crop) behaves like a 75mm lens on full frame.
What is crop factor?
Crop factor is the ratio of a sensor's diagonal size to that of a 35mm full-frame sensor. APS-C cameras have a crop factor of 1.5× (Nikon/Sony) or 1.6× (Canon). Multiply your focal length by the crop factor to get the full-frame equivalent.
How do I calculate field of view from focal length?
Field of view (in degrees) = 2 × arctan(sensor dimension / (2 × focal length)). This calculator computes horizontal, vertical, and diagonal FOV automatically based on your sensor dimensions.
What focal length is 'normal' or equivalent to human vision?
A 43mm lens on full frame (equal to the diagonal of a 35mm frame) matches the human eye's field of view. Practically, 50mm is considered the 'normal' focal length for full frame cameras.
What APS-C focal length equals 50mm full frame?
To get the equivalent of a 50mm full-frame view on APS-C (1.5× crop factor), you need a 33mm lens. On Canon APS-C (1.6× crop), you need a 31mm lens.