Why Embroidery Software Mangles Letter Spacing and Kerning When Importing Keyboard Fonts
This article explains why machine embroidery designs created from keyboard fonts (TTF or OTF) typically have uneven letter spacing, broken kerning, and awkward baseline alignment, even when the underlying font looks correct in a word processor. It covers how embroidery software handles letter placement, why kerning data is usually lost during conversion, and what to use instead for clean monogram and lettering work.
Executive summary
Letter spacing in printed text is controlled by two metadata systems built into computer fonts: advance widths (the horizontal distance the cursor moves after each letter) and kerning pairs (small adjustments between specific letter combinations such as "AV" or "To"). Both are stored inside the TTF or OTF file and used by every word processor and design application. Many embroidery workflows do not fully preserve typographic kerning and positioning behavior from TTF/OTF fonts when converting them to stitches — programs handle this differently, and some preserve more spacing information than others, but the typographic intent generally needs manual adjustment after import. The result is text that may look evenly spaced on the design screen but stitches with visible gaps, overlaps, or baseline drift.
Pre-digitized embroidery fonts in formats like BX (Embrilliance), ESA (Wilcom and Hatch), or alphabet folders of individual PES, JEF, and VP3 letter files reduce this problem because their lettering tools are built around object placement, with embroidery-specific spacing rules that account for stitch width, satin column edges, and pull compensation — concerns that typographic kerning tables were not designed for.
Definitions of key concepts
Advance width
The horizontal distance a cursor moves after drawing a letter, before drawing the next letter. Every glyph in a TTF or OTF font has an advance width baked into the font file. Without advance widths, every letter would stack in the same position.
Kerning pair
An override that adjusts the spacing between two specific adjacent letters. For example, the pair "AV" usually has a negative kerning value so the V tucks slightly under the diagonal of the A. Modern OpenType fonts can contain hundreds of kerning pairs covering common letter combinations.
Bearings (left side bearing, right side bearing)
The empty space inside a letter's bounding box, on the left and right sides. Bearings are the reason that lowercase "i" takes less horizontal space than lowercase "m" — the bearings are tighter. Like advance widths, bearings are font metadata that printing software reads automatically.
Baseline
The invisible horizontal line on which letters sit. Lowercase letters with descenders (g, j, p, q, y) drop below the baseline; uppercase letters and most lowercase letters sit on it. Baseline alignment is handled automatically by typography software; in embroidery software it must usually be re-established at import.
Embroidery letter object
A single digitized letter packaged as an embroidery object. Unlike a TTF glyph, an embroidery letter object contains stitch data (satin columns, fills, underlay) plus its own embroidery-specific bounding box, designed to align with the next letter at the satin column edge — not at an abstract typographic bearing.
Why kerning is lost during keyboard-font import
1) The conversion focuses on the outline
When embroidery software imports a TTF, the priority is extracting the outline of each letter — the closed Bézier curves that define the glyph shape — so that stitches can be generated to fill it. The font's metadata table (which stores advance widths, kerning pairs, and bearings) is in a different part of the file, and how completely an embroidery program reads this metadata varies by vendor. Some preserve advance widths reasonably well; others discard everything except the shape.
2) Font units do not match embroidery units
TTF advance widths are stored in font design units (typically 1000 or 2048 units per em). Embroidery software works in millimeters or 0.1 mm units. Converting font units to embroidery units requires the correct em-size and DPI mapping, and the result still has to be reconciled with the visible stitched edge of each letter rather than its outline edge — so even when the conversion is performed correctly, the typographic intent does not transfer cleanly.
3) Modern kerning lives in GPOS
Modern OpenType fonts can store kerning either in the older "kern" table or in the newer GPOS (Glyph Positioning) table, which is part of the OpenType layout system. Word processors and graphic design programs include a full OpenType layout engine that interprets GPOS positioning. Embroidery import functions vary in what they support — some read basic kern table values, but full GPOS layout is not commonly implemented in embroidery programs. The result is that pair-specific kerning adjustments from modern OpenType fonts are typically not reproduced in the embroidered output.
4) Embroidery letters have stitched edges, not vector edges
Even if all the typographic metadata were perfectly preserved, it would still produce wrong-looking embroidered text. Typographic bearings are designed for ink on paper, where the edge of a glyph is the edge of its outline. In embroidery, the visible edge of a letter is the outer edge of the satin column or fill — which is offset from the original outline by half the satin column width plus pull compensation. Two embroidered letters spaced according to typographic bearings will visibly overlap or gap because their stitched edges are in different places than their outline edges.
What "mangled spacing" looks like in practice
Uneven gaps
Some letter pairs sit too close together, others have visible white space between them. This is the symptom of missing kerning pair data. Pairs like "AV", "Ta", "Wo", and "fi" are the most affected because they rely on kerning overrides in the original font.
Letters touching or overlapping
Without pull compensation accounting, the stitched satin columns are wider than their outline shapes, so adjacent letters touch even though the design preview showed clean space between them.
Baseline drift
Depending on the program and the import path, baseline behavior can be inconsistent — some imported letters may align to the typographic baseline, others to the bounding box. Letters with descenders (g, p, q, y) are the most affected, since they sit below the baseline by design and are easy to misalign during conversion. The result is that imported text may need manual baseline correction even when the original font is set up correctly.
Inconsistent letter heights
A correctly digitized embroidery font tests every letter at every supported size, with the same x-height across the alphabet. Auto-imported TTF letters use the original font's vector heights, which look identical on screen but stitch at slightly different heights once underlay and pull compensation are applied unevenly.
Why pre-digitized embroidery fonts get spacing right
Letter objects are placed by satin edge, not vector outline
A pre-digitized embroidery font defines each letter as an object whose bounding box matches the visible stitched edge, not the vector outline. When the lettering tool places one letter after another, the spacing between satin columns is the spacing between bounding boxes — which is the spacing the digitizer designed.
Embroidery-specific kerning rules
Modern lettering tools apply their own kerning rules based on letter pair geometry, satin column width, and pull compensation. These rules are tuned for embroidery, not for ink-on-paper typography, so they produce visually balanced spacing on stitched fabric — which is not the same thing as visually balanced spacing on a printed page.
Baseline is enforced by the tool
Lettering tools place every letter on a single baseline by default, with descenders dropping below it as expected. The baseline is a property of the tool, not of the font file, which means it does not get lost during format conversion.
Per-letter manual adjustment
Even with good defaults, monogram and custom name work often needs per-letter adjustment. A good lettering tool lets the user nudge individual letters horizontally, vertically, and rotationally so that final spacing is perfect. Doing this in keyboard-font conversion software is much harder because the spacing problem usually shows up after the design has already been flattened to stitches.
When the difference matters most
Three-letter monograms
Traditional three-letter monograms have a larger center letter (usually the surname initial) flanked by two smaller letters (first and middle name initials). Spacing must be tight and visually balanced. Auto-converted TTF monograms typically need manual rework to look balanced; pre-digitized monogram fonts include explicit center-letter sizing and balanced spacing as a feature.
Long names and phrases
The longer the text, the more visible kerning errors become. A 4-letter name might look acceptable; a 12-letter phrase from an auto-converted TTF will have multiple obvious spacing problems.
Script and connected fonts
Script and connected fonts depend on overlap between adjacent letters — the curve of one letter must flow into the curve of the next. This requires connector handling that is rarely produced by TTF-to-stitches conversion in the same quality as hand-digitized connectors. True script embroidery fonts include hand-built connectors between letter pairs; auto-converted TTF script fonts typically need manual repair at the join points.
Small text
Small text amplifies every spacing error because the eye perceives gaps as a percentage of letter height. A 2 mm gap at 30 mm tall is invisible; the same gap at 8 mm tall is glaring.
Common workarounds (and why they don't fully solve the problem)
Manual letter-by-letter spacing in embroidery software
Some embroidery programs let the user click each imported letter and drag it into position. This works in principle but requires the user to compensate manually for every kerning pair the font originally had — usually hundreds of adjustments for a single phrase. It is also unforgiving because once the design is flattened to stitches, the letters cannot be re-positioned without losing the digitizing.
Setting global letter spacing
Most embroidery software has a "letter spacing" or "tracking" slider. This applies a uniform offset to every letter pair, which makes the average gap larger or smaller but does not fix individual kerning pairs. The result is text that is uniformly too tight or uniformly too loose, with the same proportional errors.
Re-digitizing the text
An experienced digitizer can re-digitize the text by hand, fixing every spacing problem and adding underlay and pull compensation. This produces excellent results but takes 30+ minutes per phrase, which defeats the convenience of using a keyboard font in the first place.
Key takeaway
Letter spacing in printed text relies on font metadata (advance widths, kerning pairs, bearings) that many embroidery workflows do not fully reproduce. Even when the metadata is read, typographic spacing rules do not match embroidery spacing requirements, because embroidery letter edges are stitched satin columns offset from the original outline by pull compensation. The practical result is that converted text usually needs manual spacing and baseline correction before it stitches cleanly.
Pre-digitized embroidery fonts reduce this problem by storing each letter as an embroidery object with stitched-edge bounding boxes, and by relying on lettering tools that apply embroidery-specific spacing rules instead of typographic kerning tables. For monogram, name, and phrase work, this approach typically requires far less per-letter manual rework.
Free option: Artapli Lettering Tool
The Artapli Embroidery Lettering Tool is a free browser-based lettering tool that places hand-digitized letter objects with embroidery-specific spacing rules — not typographic kerning tables. It supports per-letter manual nudging when needed, and exports to all 8 major machine formats (PES, DST, JEF, VP3, EXP, HUS, XXX, VIP). For technical context on why embroidery fonts are different from keyboard fonts, see Why Pre-Digitized Embroidery Fonts Stitch Better Than Keyboard Fonts and Machine Embroidery Font Formats Explained: BX, PES, JEF, ESA, VP3, DST.
