Free tool
AVIXA DISCAS display size calculator
Pick the right screen before you quote it. Enter the farthest and closest viewing distance, choose the kind of content, and get the minimum image height, the diagonal in metres and inches, and the standard panel size to order. Free, and nothing leaves your browser.
Minimum image height
1.00 m
Minimum diagonal
2.04 m (81")
Nearest standard panel
86"
Front row check
OK
Simplified AVIXA V202.01 DISCAS rules of thumb: basic decision making at one sixth of the farthest distance, analytical decision making at one quarter. Estimate only, verify against the real content and the room.
The room sets the screen size, not the budget
The most common complaint after a meeting room handover is that nobody at the back can read the screen. It is almost never a resolution problem, it is a size problem: the display was chosen to fit the wall or the price, not the distance people actually sit at. Sizing from the farthest viewer first, then checking the front row, removes that argument before the panel is ordered.
How it works out
- Basic decision making, slides and video calls: image height at least the farthest distance divided by 6.
- Analytical decision making, spreadsheets and CAD: image height at least the farthest distance divided by 4.
- Diagonal follows from the height and the aspect ratio, then rounds up to a size you can actually buy.
- Nobody should sit closer than roughly one image height from the screen.
These are simplified AVIXA V202.01 DISCAS rules of thumb, good enough for a boardroom or a classroom and a sane starting point everywhere else. Designing the whole room? Avitly places displays on the real floor plan at real scale, so the sightlines you check here survive contact with the drawing.
Common questions
What is the difference between basic and analytical decision making?
Basic decision making (BDM) covers content where the viewer only needs to recognise what is on screen: presentation slides, video calls, a dashboard with large tiles, digital signage. Analytical decision making (ADM) covers content the viewer has to read in detail: dense spreadsheets, CAD drawings, code, medical or control room data. ADM demands a noticeably larger image because the smallest meaningful element on screen is much smaller, so the rule tightens from roughly one sixth of the farthest viewing distance to one quarter.
Is this the same as the AVIXA DISCAS standard?
It is the shorthand version. AVIXA V202.01 DISCAS works from the height of the smallest element in your actual content, expressed as a percentage of image height, and derives the farthest viewer distance from that. Because most people do not know their %EH figure up front, the industry uses the 1:6 and 1:4 divisors as a fast approximation. For a boardroom or a classroom this gets you within a panel size of the right answer. For a control room, a courtroom, or anything where legibility is contractual, run the full DISCAS calculation with the real content measured.
Why does the closest viewer matter?
A screen that is correct for the back row can be uncomfortable for the front row. The usual guidance is that nobody should sit closer than about one image height from the display. Closer than that and the viewer has to move their head to take in the whole picture, edges fall outside comfortable vision, and on lower resolution panels or LED with a coarse pixel pitch the pixel structure becomes visible. If the calculator flags the front row, move the first row back, or choose a finer pixel pitch.
Does aspect ratio change the panel size I need?
It changes the diagonal, not the height. The rules of thumb set a minimum image height, and diagonal is just that height plus whatever width the aspect ratio adds. A 16:10 screen of the same height has a slightly smaller diagonal than 16:9, and a 21:9 ultrawide has a much larger one. Order on height and check the diagonal second, otherwise a wide screen that looks impressively large on paper can still be too short to read from the back.
What if the calculated size is bigger than any panel available?
Once you go past about 110 inches, flat panels stop being practical and expensive. The options are direct view LED, which scales to any size and lets you choose pixel pitch to suit the front row, projection, which is cheaper per square metre but needs ambient light control, or splitting the content across two displays so each half serves part of the room. Moving the back row forward is usually the cheapest fix and worth checking before you price a video wall.
Does resolution affect the answer?
Indirectly but importantly. These rules size the image for legibility of content at a given scale; they assume the display resolves that content. A 98 inch screen showing 1080p over a 3 metre viewing distance will be technically large enough yet still look soft, because the viewer is close enough to resolve individual pixels. Pair the size this tool gives you with a resolution check: at roughly one image height away, 4K holds up on almost any panel size, while 1080p starts to break down past about 75 inches.
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