A variable font carries a continuous range of styles in a single font file by interpolating between master designs. Even if you only intend to ship static fonts, the same setup is the easiest way to manage a family — every named instance can be exported with one click.
Setup
Set up a variable font by adding at least one axis and at least two compatible masters along that axis: a default master that holds the variable font's default rendering, and one or more masters at other positions on the axis. Most variable-font properties are configured through the Font Properties panel (Ctrl+F2).
Decide which axes (Weight, Width, Slant, Optical Size, etc.) and which master positions you need before drawing too much. The shape of the design space affects how every glyph in the font has to be drawn.
Editing Across Layers
When working with multiple masters, the Masters and Layers panel toolbar has an Edit Across Layers toggle. With it on, supported edits — moving points, deleting points, transforming — apply to every compatible layer at once.
Compatibility
Interpolation only works across masters whose contours have the same point count, point types, and order. The Masters and Layers panel shows a red icon next to each incompatible master, with letters identifying the kind of mismatch (outlines, contour count, node types, direction, start point, transforms, anchors). Use Make Compatible on the panel toolbar to fix common issues automatically.
Avoiding Rendering Artefacts
Overlapping contours are explicitly allowed in variable fonts. A few patterns to be aware of:
•Partly equal paths. Adjacent contours that share segments produce visual artefacts during rasterization. Keep contour boundaries distinct.
•Overlaps inside a contour. A contour that fully encloses another contour can confuse the rasterizer's fill rule. Consider Remove Overlap on those glyphs.
•Kinks. A kink can appear during interpolation when three or more points stay collinear, the angle between segments is different across masters, and the segment-length ratio is also different. The kink shows up most strongly at the midpoint between masters. FontCreator can detect kinks and offer to fix them automatically.
Smart Components
Not every variation needs to be wired up as a font master. Smart Components let a single glyph carry alternate layers along its own internal axes — useful for designed elements that vary independently of the rest of the font, such as a serif that can grow or a counter that can widen.
PostScript Names on Named Instances
Each named instance (in the fvar table) can carry its own PostScript name, which clients may use when emitting PDF or PostScript output. Set them in the Instances section of the Font Properties panel.
Point Reduction
Variable fonts naturally accumulate points. Manually reducing geometry that doesn't influence interpolation is rarely worth it: the file-size saving is small and the maintainability cost is real.
Further Reading
For tutorials and worked examples, see the online FontCreator Tutorials.
