SCREEN SIZE GUIDE:

TRADE SECRET:
Don't limit yourself strictly to light switches in trying to control lighting levels in your room. Rooms with zone lighting present problems in keeping the lights up while avoiding hot spots, glare or excess light on the presentation screen that can degrade the quality of your visuals. Even in facilities with very high ceilings, the maintenance staff can usually be prevailled upon to remove specific light bulbs so you don't need to turn down or shut off entire zones.

	VERY SMALL GROUPS		For meetings with up to 10 attendees, perhaps in a conference room or other intimate setting, a large-screen video monitor (screen diagonal up to 94 centimeters / 37 inches) is adequate. Placing your laptop so other people can see it generally is not. A helpful rule of thumb for calculating optimum screen size is to use a 53-centimeter (21-inch) monitor for the first three attendees, then add 5 centimeters (2 inches) of screen diagonal for each additional person in the audience. That's an informal guideline - monitors come in a variety of standard sizes, so you'll have to match your math to what's available. The farther people sit from the screen, the larger the monitor will need to be. But it's amazing what a difference moving from a monitor to a projector can make, in terms of impact, even for an audience of this size.
	SMALL GROUPS	Sessions that involve a dozen to two dozen attendees will quickly outgrow basic conference rooms. In "breakout" rooms where attendees sit classroom- or theaterstyle within about five meters of the screen, small projection screens with diagonals up to 200 centimeters (60 inches) are in order. Use the same informal rule of thumb to determine optimum screen size: Start at 53 centimeters (21 inches) for the first three to five attendees, then add 5 centimeters (2 inches) of screen diagonal for each additional person in the audience. If participants are seated around a horseshoe-shaped table or otherwise arranged so it will be awkward to force everyone to look at the same screen, use several large-screen monitors instead. Have them "daisy-chained" together (connected to the same feed) and positioned so everyone in the room has a clean line of sight to at least one monitor. Reinforce your communication by using a projection screen so your audience can see how you are interacting with the same information displayed on their monitors. If cost is an issue simply resort to a larger screen and brighter projector - it will be cheaper and far less complicated in the long run.
	LARGE GROUPS	In auditoriums, theaters, hotel ballrooms and other large venues, the math is not as simple. Use the sliding scale below to determine approximately how large your projection screen will need to be. If more than one screen is to be provided, divide your expected audience by the number of screens and calculate accordingly. When placing multiple screens, room configuration also needs to be considered. In boxcars, placing smaller screens along the sides part way back from the stage may provide better lines of sight and viewing distances than directing everyone's attention to one large screen at the very front of the room. Should you be addressing several thousand people, placing screens across the back of the room and allowing people to turn around and look at them instead of at you is an option worth considering.

In terms of viewing distance, the front rows of a theater - or classroom - style arrangement should be as far from the screen diagonal, the back rows no more than five times as far from the screen as the screen diagonal.

For example, when presenting in a room with a 11.5 feet screen diagonal, the first rows should be about 23 ft. from the screen, the back rows no more than about 60 ft. away. Should you be addressing several thousand people, placing screens across the back of the room and allowing people to turn around and look at them instead of at you is an option worth considering.