Enter the values of R1, R2, and H into the calculator to determine the volume of the Plus To Minus Cyl Calculator, and this calculator can also evaluate any of the variables given the others are known.

## Plus To Minus Cyl Formula

The following formula is used to calculate the volume of a Plus To Minus Cyl Calculator:

V = π * (R1^2 - R2^2) * H

Variables:

- V is the volume of the Plus To Minus Cyl Calculator
- R1 is the radius of the larger circle
- R2 is the radius of the smaller circle
- H is the height of the cylinder

To calculate the volume of the Plus To Minus Cyl Calculator, subtract the square of the radius of the smaller circle from the square of the radius of the larger circle. Multiply the result by π (pi) and then multiply by the height of the cylinder.

## What is a Plus To Minus Cyl?

A Plus to Minus Cyl, also known as a cylinder conversion, is a method used in optometry to convert the format of a prescription for eyeglasses or contact lenses. This conversion is necessary because different manufacturers and countries use different notation systems. In a plus cylinder notation, the cylinder power (which corrects for astigmatism) is added to the sphere power (which corrects for nearsightedness or farsightedness). In a minus cylinder notation, the cylinder power is subtracted from the sphere power. The conversion between the two notations involves changing the sign of the cylinder power, and adjusting the axis value by 90 degrees. This conversion does not change the optical power of the prescription, but merely represents it in a different format.

## How to Calculate Plus To Minus Cyl?

The following steps outline how to calculate the Plus To Minus Cyl.

- First, determine the initial cylinder power (+).
- Next, determine the final cylinder power (-).
- Next, subtract the final cylinder power from the initial cylinder power to get the Plus To Minus Cyl.
- Finally, calculate the Plus To Minus Cyl.
- After inserting the values and calculating the result, check your answer with the given example problem.

**Example Problem:**

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

Initial cylinder power (+) = +2.50

Final cylinder power (-) = -1.75