Aspect Ratio: The One Decision Most LED Screen Buyers Get Wrong

Every television and monitor you have ever bought came in one of two shapes: 16:9 or, if it was old, 4:3. You never had to think about it. The shape was decided for you, and every piece of content in the world — films, ads, presentations, cricket broadcasts, YouTube — was made to fit it.

A modular LED display is different. It is built from modules, which sit in cabinets, which stack into a wall — and that wall can be almost any rectangle you like. Nine metres wide and two metres tall? Fine. A perfect square? Fine. That freedom is the single best thing about LED, and it is also the reason so many screens end up with black bars down the sides, stretched faces in the video, or a content bill that never stops arriving.

This guide explains why aspect ratio matters, why the answer is different indoors and outdoors, and — with full working tables — exactly which module, which cabinet and which grid to choose so that the finished wall lands on 16:9.

1. The world is built in 16:9

16:9 is not a preference. It is a standard, written into how video is produced, broadcast and delivered.

The industry bodies say the same thing. The OAAA/IAB Digital Out-of-Home Creative and Content Guide — the reference agencies use when building DOOH campaigns — lists 16:9 and 9:16 as the primary full-screen formats, with 16:10 as the alternative, and 1920×1080, 1280×720 and 3840×2160 as the standard resolutions. Anything outside that list is a custom build the agency has to be asked, and paid, to produce.

Two practical consequences:

• If your screen is 16:9, content just works. Every laptop, every media player, every agency file, every stock video, with no conversion.
• If your screen is not 16:9, someone has to make content specifically for it — forever. Not once. Every campaign, every new video, every seasonal creative.

Where 4:3 still lives

4:3 was the shape of standard-definition television and the older projector generation, and it survives in three places: legacy archive footage, some industrial and CCTV camera outputs, and older classroom projector content. It is worth knowing about, but in 2026 it is almost never the right shape to build a new screen in. If you have a 4:3 archive you must show, it displays comfortably inside a 16:9 screen with side pillars — the reverse is far more painful.

And the fast-growing third shape: 9:16

Vertical. Standees, lift lobbies, mall totems, QSR menu rails, retail window displays. This is simply 16:9 rotated, and everything in this guide applies to it with width and height swapped. Instagram Reels, YouTube Shorts and most social creative are already 1080 × 1920, so a 9:16 screen inherits the same "content just works" advantage.

2. What actually happens when the ratio doesn't match

When a 16:9 video meets a screen that isn't 16:9, your player has exactly four options, and all four cost you something.

Letterbox / pillarbox — you paid for pixels you don't use. The content is fitted inside and the leftover area goes black. On a screen where you bought 20 square metres of LED, you might be lighting 17. The bars are also visually obvious at night on an outdoor site.

Stretch — the content is distorted. Faces get wide, logos get squashed, circular brand marks become ovals. Marketing teams notice this immediately and it looks unprofessional. Never accept a screen that requires permanent stretching.

Crop — you lose the edges. The player zooms until the frame fills, and heads, prices, phone numbers and legal text fall off the sides. This is the most dangerous option because it usually looks fine on the test loop and destroys a real campaign later.

Re-master — the honest option, and the expensive one. Content is rebuilt at the screen's native resolution. Correct, beautiful — and a recurring cost for the life of the screen.

How close is close enough?

Not every wall lands on exactly 1.7778. The useful question is how much black bar a near-miss actually produces. Here is the real answer in millimetres:

The working rule we use at Lumina:

• Within 2 % of 16:9 — treat it as 16:9. The bar is a few millimetres and invisible from viewing distance.
• 2 % to 5 % — acceptable, but design the content with a safe margin so nothing important sits at the edge.
• Beyond 5 % — this is now a custom-content screen. Make that decision deliberately, with a content budget attached.

3. When custom is genuinely right

Being able to build any shape is not a flaw — it is the reason LED wins jobs that no television can. Custom is the correct choice when:

• The content is made for the screen, not borrowed. A 12 m × 2 m ribbon board above a stadium concourse, an anamorphic corner display, a curved reception feature, a facade wrapped around a column. These exist to be bespoke, and the creative is budgeted alongside the hardware.
• The architecture dictates the opening. A hoarding frame, a lift lobby recess, a shopfront transom. Physical constraints win, and the screen fills them.
• The screen is the artwork. Motion graphics, generative content, brand environments — where there is no external video to be compatible with.
• You want a striking format on purpose. Ultra-wide 32:9 and 21:9 walls are extremely effective for lobbies and control rooms, and content for them is a one-time design exercise.

But when a screen has to accept other people's content — a rented ad slot, a client's presentation, a live feed, a broadcast, a customer's USB stick — build it in 16:9 or as close as the cabinets allow. That includes almost every DOOH and OOH advertising site, retail and mall screen, boardroom, auditorium, broadcast backdrop, stadium main screen, showroom, hotel lobby and QSR menu board.

The freedom to build any shape should be spent on the jobs that need it — not on the ordinary screen where it silently becomes a permanent tax on your content.

4. Module families: one universal size, and two specialists

This is the part most guides skip, and it is the reason a single "best cabinet" answer does not exist. There are really only three module grids you will meet, and they do not split neatly into "indoor" and "outdoor" — the main one does both.

320 × 160 mm — the universal module, indoor and outdoor

320 × 160 mm is the conventional module size of the LED industry, and it is the most common size for indoor and outdoor alike. If you order a module without specifying anything else, this is what arrives. It is the most manufactured, most stocked and most price-competitive footprint in the world — and it is now made in every construction that matters:

• SMD — the mainstream, indoor and outdoor, P1.25 to P10
• GOB (glue-on-board) — the ruggedised version for touchable and high-traffic screens, same footprint
• COB (chip-on-board) — and this is the new part: COB is now available in 320 × 160 mm as well, so the newest technology drops straight into the cabinets you already use

That is the single strongest reason to design around it. One footprint, every technology, indoors and out — and, as Section 6 shows, a cabinet grid that reaches exact 16:9 in twelve panels.

250 × 250 mm — the rental and staging module

250 × 250 mm is a square module, and in practice you meet it on rental series panels: the quick-lock, curve-capable, road-case cabinets used for concerts, weddings, exhibitions and corporate stages.

It goes into two cabinet sizes, and really only two:

Both sit on a 500 mm grid, which is what makes rental walls so quick to size on site: every dimension is a multiple of half a metre.

The same 250 mm grid also appears in 1000 × 1000 mm fixed outdoor cabinets (4 × 4 modules), but that is the minority case. For fixed outdoor work, the 320 × 160 outdoor module in 960 × 960 mm cabinets is far more common.

192 × 192 mm — the P3 and P6 grid

192 × 192 mm is a real module and you will see it quoted. It exists for one specific reason, and it is worth understanding so that you are neither steered onto it by accident nor talked out of it when it is genuinely the right choice.

A module size only works at pitches that divide into it evenly. Here is what each common module can actually do:

(P3.08 and P6.67 are the trade names; the exact pitches are 3.0769 mm and 6.6667 mm, which is what makes the pixel count come out whole.)

Look at the two bolded entries. P3 and P6 are the only pitches that 192 × 192 covers and 320 × 160 cannot — 320 ÷ 3 = 106.67, which is not a whole number of pixels, so a true P3 module simply cannot be built at 320 × 160 mm. That is the entire reason the size exists, and it splits cleanly into two products:

• Indoor 192 × 192 is a P3 module, and it sits in a 576 × 576 mm cabinet — 3 × 3 modules, a square cabinet on a 192 mm grid. If you are quoted a genuine indoor P3 screen, this is very likely what is inside it.
• Outdoor 192 × 192 is a P6 module. It is a comparatively rare size internationally, but it is well established in India and you will meet it on mid-range outdoor work.

Away from those two pitches, the market has moved around it:

• Want roughly P3 indoors on the mainstream grid? P3.08 on a 320 × 160 module gives 104 × 52 pixels — visually indistinguishable from P3.
• Want roughly P6 outdoors on the mainstream grid? P6.67 on a 320 × 160 module gives 48 × 24 pixels.
• Everything finer or coarser — P1.25, P2, P2.5, P4, P5, P8, P10 — is already covered by 320 × 160 and 250 × 250.

So 192 × 192 is the specialist grid for P3 and P6 — the right answer at those two pitches, and the wrong one at any other. If it is quoted to you at some other pitch, ask what the 320 × 160 equivalent would be.

Which module goes in which cabinet

Fixed arithmetic — every division has to come out a whole number:

What this means for aspect ratio

Here is the consequence, and it is a happy one:

• The indoor 320 × 160 cabinets are 4:3 or 2:3 shaped, so they reach exact 16:9 in very small grids — a 4 × 3 grid of 640 × 480 cabinets is just 12 cabinets, 2.56 × 1.44 m. Indoor walls are small, and this family hits 16:9 exactly at exactly those sizes.
• Square cabinets — 500, 576, 960 and 1000 mm — need a 16 × 9 grid, 144 cabinets, for an exact hit. That sounds like a lot until you notice what it measures: 16 × 9 cabinets of 1000 × 1000 mm is 16.00 m × 9.00 m, precisely a large hoarding. Square cabinets land on 16:9 exactly at outdoor sizes.
• Tall 1:2 rental cabinets (500 × 1000 mm) would need a 32 × 9 grid, which is impractical — so for rental, either use the near-16:9 grids in Section 9, or mix in 500 × 500 cabinets to trim the wall back to shape.

The geometry is not fighting you. Each family lands on 16:9 in the size range it was designed for. You just have to know the grid.