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In an earlier article, How Big Should Your Display Be? A Friendly Guide to the AVIXA DISCAS Standard, we walked through the classic question: how big does a display need to be for a meeting room? The short answer was never "whatever looks good" or "whatever the datasheet recommends" — it comes down to the AVIXA DISCAS method: define the farthest viewer, define the type of content, and calculate the image height that content needs to stay readable.
That article assumed something simple: that the content fills the screen. Walk into a modern hybrid meeting room, though, and that assumption often breaks down.
The 60-second version
- In Teams Front Row, Zoom, Webex, or an LED video wall, the physical screen and the content you need to read are not the same thing — content usually shares the display with video tiles, chat, or other windows.
- Size the display for the content window, not the panel around it — figure out what share of the display height the readable content actually occupies, then scale up from there.
- Most video conferencing rooms are still BDM (Basic Decision Making) — the same DISCAS math from our first article still applies, it's just applied to a smaller area.
Why a bigger screen doesn't always mean a bigger picture
Picture a Microsoft Teams Room using Front Row layout, or a Zoom call with shared content and a gallery of remote faces. The physical display might be a generous 21:9 panel. But the shared PowerPoint you actually need to read isn't using the whole screen — it's sharing space with video tiles of remote participants, a chat panel, maybe a reactions bar. The screen is big. The part of it carrying the information you actually need to read is smaller.
The same thing happens in control rooms and command centres, just at a larger scale: an enormous LED wall might host a dozen independent windows — maps, dashboards, camera feeds — and an operator only needs to read the one small window showing an alarm.
This is where a lot of display-sizing goes wrong. The right question isn't how big is the display? It's: how big is the part of the image people actually need to read?
Why the full display size can be misleading
DISCAS calculates based on displayed image size — the image, not the panel it happens to sit on. In a simple presentation room, those two things are nearly identical: a 16:9 slide deck fills a 16:9 display, so using the full screen height as your starting point is a reasonable simplification.
In a conferencing layout, that simplification stops holding. A single screen is often divided into zones: shared content in one area, people in another, chat or reactions along the side. The smallest important element — a line of text in a shared document, a label in a spreadsheet, a note on a shared whiteboard — might only ever appear inside the content window, never across the full display.
So when we apply DISCAS to video conferencing rooms, we calculate from the effective content image height: the height of the window that actually carries the information people need to read. In practical terms, the content window becomes "the display" for the purposes of the calculation — the physical panel around it is just the frame.
The approach: treat the content window as the image
For most video conferencing rooms, the right DISCAS category is still Basic Decision Making (BDM) — people need to read presentation titles, agenda points, shared documents, chat messages, diagrams. They usually don't need to resolve individual pixels the way a radiologist or a CAD reviewer does.
The BDM formula itself doesn't change:
Image Height = Farthest Viewer ÷ (%EH × 200)
(Using %EH as a decimal — e.g. 0.03 for 3%. You'll sometimes see this written as Farthest Viewer ÷ (%EH × 2) with %EH as a whole number like "3" — both give identical results, they're just two ways of writing the same percentage.)
What changes is what we mean by Image Height. In a standard presentation room, it can be the full display height. In a Teams Front Row layout, a Zoom call with shared content, or a control-room wall built from several independent windows, it needs to be the height of the relevant content window — not the panel it's displayed on.
Worked example: a 21:9 Microsoft Teams Front Row room
Let's say the farthest viewer sits 6.0 m (600 cm) from the front-of-room display, and we use a solid BDM default of 3% Element Height for general shared content.
| Step | Calculation | Result |
|---|---|---|
| Required content image height | 600 cm ÷ (0.03 × 200) | 100 cm |
| If content filled a full 16:9 display | 100 cm × 2.04 | ~204 cm (80 in) diagonal |
| But the content window is only 60% of the panel's height | 100 cm ÷ 0.60 | 167 cm — the required total image height |
| Minimum diagonal on a 21:9 panel | 167 cm × 2.54 | ~424 cm (167 in) |
(A quick note so the numbers don't blur together: the 2.54 here comes from the diagonal-to-height ratio of a 21:9 rectangle — a coincidence of geometry, not the 2.54 cm-per-inch conversion factor. They're unrelated, even though the digits match.)
This doesn't mean every Teams Room needs a 167-inch display — most don't come anywhere close to that content ratio. It means that if the readable content area only occupies 60% of the display height, you have to size the physical panel so that the content window inside it still meets the DISCAS requirement. Skip that step, and you can end up with an expensive, genuinely large display that's still too small for the people using it.
The same principle applies to LED walls and control rooms
This isn't specific to Microsoft Teams. It applies to any system where content is arranged in independent windows: LED walls, command centres, network operations centres, broadcast monitoring walls.
A control room might have a very large LED wall overall, but an operator may only need to read a map label, an alarm message, or a dashboard value inside one much smaller tile within it. In that case, the DISCAS calculation belongs to that tile — not the total wall size. A large wall can still fail its purpose if the information that matters is squeezed into a window that's too small.
When should ADM be used instead?
Most video conferencing rooms are BDM spaces — shared slides, notes, webpages, whiteboards, and general documents fall under Basic Decision Making because people need to understand the information, not inspect it pixel by pixel.
ADM becomes the right choice when the conferencing room doubles as a space for detailed technical review: CAD drawings, engineering schematics, medical images, surveillance analysis. In that case, apply the ADM formula to the relevant content window specifically, using the vertical resolution of that window — not automatically the full resolution of the physical display, since the window is very likely running at a lower effective resolution than the panel itself.
A practical checklist for sizing conferencing and control-room displays
When we size a display for a video conferencing room, we typically work through five steps:
- Define the farthest viewer. Measure from the screen plane to the farthest seat where content must stay readable.
- Define the critical content. Is it a shared PowerPoint, an Excel sheet, a Miro board, CAD, camera video, meeting chat, or a mix?
- Identify the real content window. In Teams Front Row, Zoom, Webex, an LED wall processor, or a multiviewer, work out how much of the total display height the content people must read actually occupies.
- Select BDM or ADM. BDM for general meeting content, ADM only for pixel-critical analysis.
- Calculate from the content window, then scale up. If the content window is only 60% of the display height, divide the required content height by 0.60 to get the required total image height for the physical panel.
Key terms at a glance
- Content window
- The portion of a display that actually carries information people need to read, as distinct from the full physical panel around it (e.g. the shared-content area in Teams Front Row).
- Effective content image height
- The DISCAS "image height" recalculated for just the content window, rather than the whole screen.
- BDM / ADM
- See our DISCAS basics guide for the full definitions; most conferencing rooms use BDM.
FAQ
Should I use the full display size for DISCAS calculations in Microsoft Teams or Zoom rooms?
Not always. If the shared content doesn't fill the full display, the more accurate approach is to calculate from the height of the shared content window — that's the part of the image that actually has to stay readable.
Are 21:9 displays better for Teams Rooms?
They can be excellent for Front Row layouts because they give more horizontal space for remote participants, shared content, and meeting panels. But the wider aspect ratio doesn't automatically solve readability — the shared content area still needs to be large enough for your farthest viewer.
Should video conferencing rooms use BDM or ADM?
Most should be calculated as BDM, since the content is usually general meeting information. Reserve ADM for spaces that genuinely require pixel-level analysis.
Does a bigger LED wall always mean better readability?
No. A large LED wall can still display unreadable content if the important window inside it is too small. The calculation should always follow the actual content layout, not the total panel size.
DISCAS gives us the method — but the room's layout tells us where to apply it. In modern collaboration rooms, the display is no longer one big image; it's often a composition of windows, and the smallest important window is usually where the real design work begins. If you're planning a Teams Room, a 21:9 Front Row installation, or a control-room video wall, get in touch with our team to calculate the right display size before hardware decisions are made.