EVERYDAY CLARITY
Photography Focal Length Calculator
What equivalent focal length gives the same field of view on the reference format? Enter the stated values to calculate this model.
Your result
Reference-format equivalent focal length
mm
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Lens focal length (mm) | Enter lens focal length in mm; use the same basis as the other measurements. |
| Crop factor (1) | Enter crop factor in 1; use the same basis as the other measurements. |
Understanding your result
Read Reference-format equivalent focal length (mm) in the units and model stated on this page. The formula equivalent=focal*crop defines the relationship; measurement accuracy and model applicability are separate from numerical precision.
Common mistakes
- Mixing input units or changing the physical meaning of a variable without changing the model.
Check your calculation
- Use the worked example as a known reference case, then change one input at a time and check the direction and units of the response.
Calculation checks, sources and review limits
What equivalent focal length gives the same field of view on the reference format?
What equivalent focal length gives the same field of view on the reference format? Enter the stated values to calculate this model.
Common uses
- What equivalent focal length gives the same field of view on the reference format
How it works
equivalent=focal*crop
Worked example
Enter Lens focal length: 50 mm; Crop factor: 1.5 1. Results: Reference-format equivalent focal length: 75 mm.