You'll need: FontCreator (Windows or macOS) and a font with most of its Latin glyphs already drawn.

Glyph spacing is the white space each character carries on its left and right. Get it right and your font reads cleanly at every size; get it wrong and no amount of kerning will rescue it. This tutorial shows how to use the optical metrics in FontCreator's font editor to set balanced side-bearings automatically, how spacing differs from kerning, and how to fine-tune the result by hand before you start pairing letters.

While designing your font you can add characters and glyphs without worrying too much about the metrics of each glyph. But before you consider adding kerning, you must ensure that the spacing between glyphs is optimal.

Spacing vs. kerning — what's the difference

These two terms get mixed up constantly, so it helps to separate them before you touch any controls.

• Spacing (side-bearings) is per-glyph. Every glyph has a left side-bearing and a right side-bearing — the gap built into the glyph itself. Spacing answers the question "how much room does this single letter need around it, regardless of its neighbours?"
• Kerning is per-pair. It is a correction applied only to specific letter combinations that look too tight or too loose even after spacing is correct — classic examples are "AV", "To", and "Yo".

The order matters: space before you kern. Kerning is meant to fix the handful of pairs that good spacing can't, not to paper over spacing that was never set. If you kern first, you end up creating hundreds of pairs to compensate for poor side-bearings — and you'll have to redo them all the moment you fix the spacing underneath.

> Note: Side-bearings live on the glyph and apply everywhere it appears. Kerning lives in the font's OpenType layout data and applies only between two named glyphs. Two completely separate mechanisms.

Set spacing automatically with Auto Metrics

A font editor usually has several ways to adjust the side-bearings of each glyph, but FontCreator lets you generate those metrics for your Latin characters with optical precision. The Automatic Metrics wizard measures the actual shape of each glyph and works out how much space it should carry on each side so that, optically, the rhythm of the text looks even.

To run it:

1. Open the font you want to space.
2. From the main menu, choose Tools → AutoMetrics to open the Automatic Metrics wizard.
3. Choose the Optical Metrics option to generate the best optical space before and after each character.
4. Set the Glyph spacing factor. This is a global distance factor — a larger factor results in more spacing between glyphs, a smaller factor tightens everything up. Start with the default, preview, and adjust.
5. Apply the wizard and review the result in the Font Overview panel and in a sample text preview.

You might need to try different glyph spacing factors to find the overall density you want — that single value scales the whole font's rhythm at once.

What optical metrics actually does

To show the power of this feature, here are a couple of popular fonts spaced with it. In each example the first line is the original font and the second line is the same font after running Optical Metrics — both at font size 14, with kerning switched off so it can't override the spacing.

With serif fonts you'll notice optical metrics finds it harder to calculate good values for glyphs with bowls — combinations such as "be", "pe", and "po". These are the spots most worth checking by hand afterwards.

Optical metrics takes less than a minute per font. That's a good return when you realise glyph spacing is considered as important as the design of the glyph outlines. Font designers can do without it, but they usually spend numerous hours trying to find a good balance manually. Perfect spacing between glyphs makes a font stand out — and it avoids unnecessary kerning pairs later.

> Tip: Run Auto Metrics on a copy of your font first, compare it against the original in a sample string, and only keep the result if it reads better. The wizard is a starting point, not a verdict.

A "space before you kern" workflow

Here is the order that saves the most rework:

1. Draw the glyphs. Don't fuss over side-bearings while the shapes are still changing.
2. Run Auto Metrics with Optical Metrics across the Latin set to get a consistent baseline rhythm in one pass.
3. Proof in real words. Type strings like "nominal", "hamburgevons", and "adhesion" — words with a mix of round, straight, and diagonal letters expose uneven spacing fast.
4. Hand-correct the outliers. Fix the glyphs the optical pass struggled with (serif bowls, punctuation, accented forms) by adjusting their side-bearings directly.
5. Only now add kerning for the pairs that still look wrong — "AV", "To", "Wa" and friends.

Doing steps 2–4 first means kerning becomes a short list of genuine exceptions rather than a font-wide patch job.

Fine-tune side-bearings by hand

After the automatic pass, some glyphs always benefit from a manual touch. A glyph carries two side-bearings: the left side-bearing is the gap from the glyph origin to the leftmost edge of its outline, and the right side-bearing is the gap from the rightmost edge to the advance width. Together they decide how much air the letter has on each side, and the advance width is the left bearing plus the glyph's black width plus the right bearing. Widen a side-bearing and the letter gets more breathing room on that side; tighten it and neighbours sit closer.

You can adjust a glyph's left and right side-bearings in the Glyph panel (open a glyph by double-clicking it) — the metrics are shown and editable per glyph. Nudge the values, watch the preview, and aim for an even amount of white space marching across a line of text.

Judge spacing with a preview string

You can't space a letter in isolation — spacing only looks right between other letters. Type a preview string that repeats the glyph you're tuning between steady-rhythm controls, so uneven gaps jump out. Classic test words mix round, straight and diagonal shapes:

• nnonn, oonoo, HHOHH — surround the glyph under test with n, o and H to read its left and right gaps against known-good neighbours.
• hamburgevons, adhesion, nominal — real-word strings that expose the rhythm across a whole run.

Watch the preview as you nudge each side-bearing; the goal is an even band of white between every pair, not a fixed number.

> Watch out: Changing a side-bearing on a base glyph affects every composite that references it, and it shifts the optical balance of any pair you've already kerned. Do your spacing pass before your kerning pass so you're not chasing your own changes.

Troubleshooting

Frequently asked questions

Should I space or kern first? Space first, always. Kerning fixes the few pairs that good spacing can't; it's not a substitute for setting side-bearings.

Does Auto Metrics work on non-Latin scripts? The optical metrics feature is built around Latin characters. For other scripts, set side-bearings by hand and proof in representative text.

Will running Auto Metrics overwrite my kerning? No — Auto Metrics changes side-bearings (per-glyph spacing). Kerning pairs are separate data. That said, changing spacing can make existing kerning look wrong, which is the main reason to space before you kern.

What's a good glyph spacing factor? There's no universal number — it depends on the design. Start at the default, preview real words, and adjust up for an airier font or down for a tighter one.

Is the optical result final? Treat it as a strong first draft. Proof it, hand-correct the glyphs it struggled with, then move on to kerning.

Next: kerning

Once your side-bearings give the font an even rhythm, you're ready for the second half of the spacing job: kerning the handful of pairs that good spacing still can't fix — the "AV", "To" and "Wa" of the world. That's a topic in its own right, covered in Kerning & Autokerning a Font. Get the spacing solid here first; kerning on top of well-set side-bearings is a short, satisfying list of exceptions rather than a font-wide rescue job.

What to read next

• Kerning & Autokerning a Font — add and clean up kerning pairs once your spacing is solid, including Auto Kern.
• Draw Better Glyph Outlines — get the shapes right before you space them.