๐ท Photography
Focal Length Calculator
The thin lens relationship links subject size, image size and distance so that any three give the fourth. In practice this answers the common question of what lens is needed from the back of a room to frame a person or a stage.
How it works
Subject height
Distance to the subject
Sensor height
How much of the frame to fill
Focal length needed
Magnification
Angle of view
Image height on the sensor
Field of view at this distance
Frequently asked questions
How do I use the Focal Length Calculator?
Fill in the fields above โ the result recalculates instantly as you type. Everything runs in your browser, so the values you enter are never collected or stored.
Is this calculator free?
Yes. It is completely free, requires no account, and works on phones, tablets and desktops.