Lens Calculator

Calculate focal length, object distance, image distance, and magnification for thin lenses

Enter any two values to calculate the third (1/f = 1/d_o + 1/d_i)

Object Distance (cm):

Image Distance (cm):

Focal Length (cm):

Sign convention: Positive for real images/objects, negative for virtual. Converging lens has positive focal length.

1/f = 1/d_o + 1/d_i (thin lens equation)

M = -d_i / d_o (magnification)