Optics Lens Calculator

Calculate image distance, magnification, and image properties using the thin lens equation (1/f = 1/do + 1/di).

Inputs

Object Distance

Focal Length

Tab to move between fields

Results

Image Distance

15 cm

≈ 2 credit cards

Magnification

-0.5

Image TypeReal

OrientationInverted

Relative SizeReduced

How to Use This Calculator

Enter Object Distance and Focal Length.
Review Image Distance (cm) and Magnification.
Use Image Type and Orientation to inform your decision.
Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Focal Length

Focal Length	Image Distance	Magnification
-8,000	-29.89 cm	1
-3,000	-29.7 cm	0.99
3,000	-30.3 cm	1.01
8,000	-30.11 cm	1

What each input means

Object Distance: Distance from the object to the lens center. Must be positive.
Focal Length: Focal length of the lens. Positive for converging (convex) lenses, negative for diverging (concave) lenses.

How this is calculated

Worked example, using the default values

Identify Input Parameters
Object Distance = 30, Focal Length = 10 = 2 input(s) provided
Calculate Image Distance
Image Distance = di
15 = 15
Calculate Magnification
Magnification
-0.5 = -0.5
Calculate Image Type
Image Type
Real = Real
Calculate Orientation
Orientation
Inverted = Inverted

Engine last updated July 21, 2026. Checked against 1 independently-derived test — how we verify calculators.

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