Right-to-left digital signage: getting Persian and Arabic boards right

Right-to-left support in signage products is usually a checkbox, and a checkbox is not the same as a board a native reader would accept. The failures are consistent and mostly invisible to the person who signed it off.

Font substitution, silently

The most common fault. You choose a Latin typeface, type Persian into it, and the platform quietly substitutes whatever it has for Arabic script.

The result: your weight is gone, your metrics are wrong, the line height is different from the rest of the board, and it looks like two designs stapled together. Nobody who does not read the script notices.

Fix: upload a typeface that actually covers the script and select it explicitly. Vazirmatn is the safe default for Persian and Arabic — openly licensed, well made, correct digit forms. Noto Naskh Arabic and IBM Plex Sans Arabic are also good. For Hebrew, Noto Sans Hebrew.

Check the licence permits embedding, because uploading a font to a device is embedding it. Most open families allow it; most foundry licences do not without a specific grant.

Direction is not alignment

Right-aligning left-to-right text is not the same as rendering right-to-left text. Real direction support changes three things:

• Punctuation and brackets resolve correctly. A right-aligned Latin renderer puts the full stop and the parentheses on the wrong side, which reads as broken.
• Numbers stay left-to-right inside a right-to-left line. That is correct and expected; a renderer that reverses digits is producing gibberish.
• Mixed-script lines — a Persian sentence containing a Latin brand name — order correctly.

The test: put a sentence with a bracket, a full stop, a number and a Latin word on the board. If any of the four lands on the wrong side, the product is right-aligning, not rendering.

Numerals

Persian and Arabic content often wants Eastern Arabic numerals in prose and Western digits for prices or times — or the reverse, depending on the audience and the region.

Decide once, for the whole board, and apply it consistently. Mixed numeral systems on one screen read as a mistake even to viewers who could not explain what is wrong.

Bilingual boards

Two approaches, both valid:

Side by side. Two text widgets in adjacent cells, one per language. Good when both audiences are present simultaneously and the content is short — a welcome, opening hours, a warning.

Alternating. Two layouts swapped on a rotation. Good when the content is long enough that splitting the board would make it unreadable in both languages, which is most content.

The mistake is doing the first with paragraph text, producing two columns of tiny type that neither audience reads.

Line length and leading

Arabic script needs more vertical room than Latin at the same nominal size — ascenders, descenders and diacritics all extend further. A layout tuned for English will look cramped, and diacritics may clip against the row above.

Give right-to-left text more line height and a slightly larger box than the equivalent Latin block.

The review that catches everything

Show the real board on the real screen to somebody who reads the script.

Not a screenshot in a chat window, not a preview on a laptop — the board, on the wall, at the size it will be read. Reversed punctuation, wrong-form numerals and a silent font substitution are obvious to a native reader in about one second and invisible to everyone else indefinitely.

Our RTL and typefaces guide covers the mechanics, and the template gallery includes Persian and Arabic boards you can import and compare against.