Enter either the optical power (in diopters) or the focal length into the calculator to determine the missing variable.

Dioptric Power (Diopters) Calculator

Enter either optical power (diopters, m⁻¹) or focal length to calculate the other. Uses the thin-lens approximation in air: D = 1 / f (f in meters). Negative values indicate diverging lenses.

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Dioptric Power (Diopters) Formula

The following formula is used to calculate optical power (in diopters) for a given focal length. This uses the thin-lens optical power approximation in air, where power equals the reciprocal of focal length in meters.

P = \frac{1}{f}

Variables:

  • P is the optical power (dioptric power) in diopters (D), where 1 D = 1 m−1
  • f is the focal length in meters (m)

To calculate optical power in diopters, take the reciprocal of the focal length (in meters). A larger magnitude of diopters corresponds to a shorter focal length.

What is Dioptric Power (Diopters)?

Dioptric power is a measure used in optics to describe the refractive power of a lens. It is defined as the reciprocal of the focal length in meters (D = 1/f). A lens with a higher magnitude of diopters has a shorter focal length and bends light more strongly. Diopters are commonly used to describe lens power in optics and in vision correction contexts.

How to Calculate Dioptric Power (Diopters)?

The following steps outline how to calculate optical power in diopters.

  1. First, determine the focal length of the lens (f) in meters.
  2. Next, take the reciprocal of the focal length to find the optical power in diopters using the formula D = 1 / f.
  3. Finally, calculate the optical power (diopters).
  4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Focal length (f) = 0.5 meters

Optical power (D) = 2 D