Focal Length for Framing
Find the focal length needed to frame a subject of a given size at a set distance.
About Focal Length for Framing
For a subject to fill the width of the frame, the focal length equals the effective sensor width times distance divided by subject width. This framing math lets you pick the right lens before the shoot so the subject is framed as intended at the chosen stand position.
Formula
Focal Length for Framing
Focal length = sensor width x distance / subject width
- sensor width
- Effective sensor width from crop factor
Worked example
With the default values below, Focal Length for Framing returns Focal Length of 120. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Subject distanceminimum 0.1
- 10
- Subject widthminimum 0.1
- 2
- Crop factorminimum 0.5
- 1.5
Results
- Focal Length
- 120 mm
- Full-Frame Equivalent
- 180 mm
- Frame Guidance
- Telephoto
Step by step
- 1Values used
- 2Focal Length for Framing
- 3Focal Length= 120 mm
- 4Full-Frame Equivalent= 180 mm
- 5Frame Guidance= Telephoto
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Focal Length for Framing calculated?
Focal length = sensor width x distance / subject width For a subject to fill the width of the frame, the focal length equals the effective sensor width times distance divided by subject width.
Why does Focal Length for Framing matter?
This framing math lets you pick the right lens before the shoot so the subject is framed as intended at the chosen stand position.
What values do I need to enter?
This calculator takes 3 inputs: Subject distance, Subject width, Crop factor. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.