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Both calculators run independently — change the inputs on either side to compare results.

Focal Length Calculator

Find the focal length of a lens given the distance to the object and the distance to the formed image. Essential for photographers, opticians, and physics students working with thin-lens optics.

Object Distance (cm)

Image Distance (cm)

Fill in the required fields to see your result.

Optics

Lens Focal Length Calculator

Compute the focal length of any thick or thin lens from its refractive index, surface curvatures, and center thickness using the lensmaker's equation. Essential for optical designers, physics students, and DIY telescope builders.

Refractive Index of Lens Material

Radius of First Surface (cm)

Radius of Second Surface (cm)

Lens Thickness (cm)

Fill in the required fields to see your result.

Key differences

	Focal Length Calculator	Lens Focal Length Calculator
Category	Optics	Optics
Inputs required	2	4
Result	Focal Length (cm)	Focal Length (cm)
What it does	Find the focal length of a lens given the distance to the object and the distance to the formed image. Essential for photographers, opticians, and physics students working with thin-lens optics.	Compute the focal length of any thick or thin lens from its refractive index, surface curvatures, and center thickness using the lensmaker's equation. Essential for optical designers, physics students, and DIY telescope builders.