Precise Typography with Font Metrics
Ever tried to align a graphic to the x-height of your text, or size a text frame to exactly fit the cap height? Without knowing the font’s actual measurements, you’re left guessing and nudging.
This has been a long-standing limitation in InDesign. When scripters ask on the Adobe Community forums how to access font metrics, the answer is blunt:
“Scripting does not provide direct access to fonts… the answer is no, alas.”
The workarounds are painful. The most common approach: create a text frame containing the letter “x”, convert it to outlines, then measure the resulting shape. Someone even built a dedicated script just to automate this process. But as one expert warns:
“I don’t think anything can be slower than converting to outlines. I think it’s the most processor intensive (and buggy) function in InDesign.”
And the results aren’t even guaranteed to be accurate—some fonts “won’t give 100% sharp heights.”
Starting with version 1.0.4, Sidekick bypasses InDesign entirely for this. It reads font metrics directly from the font files themselves—the authoritative values defined by the type designer. X-height, cap height, ascender, descender, all with complete accuracy. No workarounds, no approximations, no converting to outlines.
See It in Action
Watch Sidekick create a type specimen with mathematically precise baseline alignment:
What Are Font Metrics?
Font metrics are the measurements baked into every font file that describe the typeface’s vertical proportions:
- x-height: The height of lowercase letters like “x”
- Cap height: The height of capital letters
- Ascender: How far letters like “b” and “d” extend above the x-height
- Descender: How far letters like “p” and “g” drop below the baseline
- Units per em: The font’s internal coordinate system
These values are in font units. To get real measurements, you divide by unitsPerEm and multiply by point size. For example, with a 12pt font where unitsPerEm is 1000 and xHeight is 500:
Actual x-height = (500 / 1000) × 12 = 6ptWhy This Matters
Without font metrics, precise typographic work requires trial and error. With them, Sidekick can:
- Position objects relative to text—align a rule to the x-height, place an icon at cap height, or snap a shape to the baseline
- Size text frames precisely—make a frame exactly tall enough for the cap height, or calculate the exact height needed for a specific number of lines
- Align baselines to guides by calculating the exact frame position needed
- Create consistent vertical rhythm across different typefaces
- Build type specimens that showcase fonts at their true proportions
How It Works
The new get_font_metrics tool scans your system fonts and Adobe Fonts, caching the results for fast lookups. When you ask Sidekick to position text precisely, it can query the metrics for any installed font and calculate the exact placement.
The tool searches across font family names, PostScript names, and full names—so whether you ask for “Helvetica”, “Helvetica-Bold”, or “Helvetica Neue Bold”, it’ll find the right font.
Getting Started
Just ask Sidekick to create something that requires precise positioning—like a type specimen or a layout with aligned baselines. It will automatically use font metrics when needed.
If you’re using Adobe Fonts that aren’t being found, you may need to download them locally through Creative Cloud. Some Adobe Fonts are loaded on-demand and aren’t cached until you explicitly download them.
Font metrics support is available now in Sidekick 1.0.4 and later. The connector updates automatically, so you may already have it.