## October 2015: Front Projection Tip of the Month Part 1

### Calculating your Screen Dimensions (Part 1) By Dave Rodgers (Marketing Manager of Elite Screens & EPV® Screens)

Garden Grove, CA - October 1, 2015 - There are many online links that can help you do this but if you pride yourself on being a screen-guy/gal,  it’s a good idea to know how to do the calculations yourself.These easy calculations will enable you to calculate the height, width and the diagonal measurements.

Look at the image above. Identify the sides to be measured. Notice that it forms a triangle.

X= width
Y= height
C= diagonal measurement

An aspect ratio is always laid out as (x:y)
Ex. A 4:3 (NTSC) aspect ratio indicates that there are 4 measured (x) units of width for every 3 measured (y) units of height.

Ergo:

• The height of the 4:3 screen is ¾  or (.75) of the width.
• The width of the 4:3 screen is 4/3   or (1.3333) of the height.

Calculate more Aspect Ratios:

16:9 (HDTV)

This means there will be 16 units of horizontal (x) measurements to every 9 units of vertical (y) measurement.

The Width(x) = 16/9 or 1.78 times the height
Ergo, 1.78 * (height) = (width)
Example. A 100” high screen will have a width of 178”

The height (y) = 9/16 or .5625 times the width
Ergo, .5625 *(width) = (height)
Example. A 100” wide screen will have a height of 56.25” (or) ≈56”

The same rules apply with other aspect ratios.

2.35:1 Cinemascope

Width = 2.35 * height
Height = .426 * width

16:10 WXGA
Width = 1.6 * height
Height = .625 * width
Calculate The Diagonal
Think way back to the high school math days. Do you remember something called the Pythagorean Theorem? Even if you don’t, the formula is mercifully easier than the name is. All you need is the width and height of your projection screen and this calculation does the rest.

Here are some points to remember:

X = the screen width
Y = the screen height
C = the screen diagonal

X² = a number squared (a number times itself). Example: 4² is 4*4 = 16
√ = a square root ( the opposite of a number squared). Example: √16 = 4 (Because 4*4 = 16)

To calculate, you need to get the square of both the width and height; add them together; and then (using a calculator is fastest) get the square root.

Pythagorean Theorem (determine diagonal screen size)

x² + y² =c²
Example: Find the diagonal of a screen that is 87” wide and 49” high
Step 1. Replace  “x” with the width measurement Step 2. Replace “y” with the height measurement

c² = (87² + 49² ) = (7569 + 2401 ) = 9970
*Eliminate (x²) with a square root (√).

c = √ 9970≈ 100

Answer is 100” diagonal.

Try this on any other measurements.  All that is needed is either the length or width and the aspect ratio.

About the Author: Dave Rodgers is a guest writer for numerous publications and the Marketing Manager for Elite Screens Inc., with 20-years experience in the AV and wireless communications industries. He travels worldwide playing an active role with international business development and is regularly consulted in matters of branding and new business development. David has made numerous television, radio and editorial appearances providing installers and Do-It-Yourselfers with easy solutions toward creating larger-than-life big screen applications.