Check Sign Letter Height Against Viewing Distance — Free
A sign that reads at the counter can vanish at the door. Apply your chosen height-per-distance factor to each viewing distance and see the shortfall in millimetres before the sign is made.
The proof surface
Large-print tools resize documents. This sizes lettering in space: required height from a factor you choose, compared with the letter height the sign actually has, per viewing distance.
Why the flat version breaks
Checking at arm’s length
The failure mode is distance, not the artwork on screen.
Treating one factor as universal
Typeface, contrast and lighting all move the real threshold.
Stopping at letter height
Placement and glare decide whether height is enough.
How to work the height sighting rule
Measure where a reader will actually stand, not where the designer imagines them. The lobby directory is read from eight metres away.
Enter millimetres of letter height per metre of distance — the sample uses 25 mm per metre as an illustrative planning factor. Published guidance varies by context, letterform and audience; pick the figure your project was given and record why.
Eight metres at 25 mm per metre needs 200 mm; the directory has 150, so it is 50 mm short and flagged. The room number needs 50 and has 60 — no shortfall.
Print or mock the largest sign and read it from the real spot with real readers, including low-vision users where you can. The largest shortfall leads the summary; glare, contrast, mounting height and font all sit outside this arithmetic.
What the height sighting rule replaces
| Question | Before | Visible working |
|---|---|---|
| Checking at arm’s length | The failure mode is distance, not the artwork on screen. | Choose the factor deliberately |
| Treating one factor as universal | Typeface, contrast and lighting all move the real threshold. | Compare required with actual |
| Stopping at letter height | Placement and glare decide whether height is enough. | Prototype at distance, not at the desk |
A local arithmetic aid replaces hand calculation, not expert review. No paid AI service is needed.
Run it on the samples, right here
FIRST-LOAD
Input is processed locally and a draft is saved automatically in this browser profile when storage is available. Reset to sample clears that draft; Pro history has its own clear button. A state link encodes your inputs in its URL: share only non-sensitive rows. Browser history, clipboard and anyone receiving the link may retain it. Optional AI use below leaves this device; it is not required.
Planning arithmetic using a factor you supply. Not a signage standard, code compliance or a legibility guarantee; verify with the relevant guidance and test in place with real readers.
Data note: Everything runs in this browser tab on the height sighting rule: your sign | viewing distance m | letter height mm stays on this device, nothing is uploaded, and the reading is rebuilt only when you press run.
Go deeper: the companion app files the same reading as a index card with a stamped header
The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the height sighting rule reading, and holds your drafts on this device — one free run, then $ 4 one-time for the layer that keeps filing.
The height sighting rule reading is complete for free. The optional $4 layer adds print, row CSV and the last five local reading summaries; it does not add hidden answers. Checkout is not configured yet; the article demo remains unlimited.
Open the check sign letter height against viewing distance companionBoundary
Planning arithmetic using a factor you supply. Not a signage standard, code compliance or a legibility guarantee; verify with the relevant guidance and test in place with real readers.
What this is built on
- Method: Eight metres at 25 mm per metre needs 200 mm; the directory has 150, so it is 50 mm short and flagged. The room number needs 50 and has 60 — no shortfall.
- All sample records are invented examples. The app does not fetch measurements, policies, files or personal records.
- Google’s official pricing page, fetched 2026-09-28, lists free-tier access including AI Studio. Optional formatting only; limits and availability can change. Free-tier content may be used to improve products. Never paste private records there.
Before: The failure mode is distance, not the artwork on screen. After: the height sighting rule shows the working beside each named row so the reader can change the assumption and inspect the consequence.
Optional AI formatting, not calculation
For this height sighting rule, use the free AI Studio interface only if available to you, with no paid API key. Manual entry completes the same workflow for free. Supply only fictional or non-sensitive notes. Review its output against the source; never paste unresolved questions into the numeric rows.
Format my non-sensitive notes for a height sighting rule. Return plain rows only: sign | viewing distance m | letter height mm. Preserve supplied quantities exactly. Do not guess missing values; list questions separately. Do not calculate or add advice. I will check every row before pasting into the local tool.
Accepted schema: sign | viewing distance m | letter height mm. No AI response is executed as code.