Aesthetic specifications

This vignette summarises the various formats that grid drawing functions take. Most of this information is available scattered throughout the R documentation. This appendix brings it all together in one place.

Colour and fill

Almost every geom has either colour, fill, or both. Colours and fills can be specified in the following ways:


As well as colour, the appearance of a line is affected by size, linetype, linejoin and lineend.

Line type

Line types can be specified with:


The size of a line is its width in mm.

Line end/join paramters

Mitre joins are automatically converted to bevel joins whenever the angle is too small (which would create a very long bevel). This is controlled by the linemitre parameter which specifies the maximum ratio between the line width and the length of the mitre.


The border of the polygon is controlled by the colour, linetype, and size aesthetics as described above. The inside is controlled by fill.



Shapes take five types of values:

Colour and fill

Note that shapes 21-24 have both stroke colour and a fill. The size of the filled part is controlled by size, the size of the stroke is controlled by stroke. Each is measured in mm, and the total size of the point is the sum of the two. Note that the size is constant along the diagonal in the following figure.

sizes <- expand.grid(size = (0:3) * 2, stroke = (0:3) * 2)
ggplot(sizes, aes(size, stroke, size = size, stroke = stroke)) + 
  geom_abline(slope = -1, intercept = 6, colour = "white", size = 6) + 
  geom_point(shape = 21, fill = "red") +


Font face

There are only three fonts that are guaranteed to work everywhere: “sans” (the default), “serif”, or “mono”:

df <- data.frame(x = 1, y = 3:1, family = c("sans", "serif", "mono"))
ggplot(df, aes(x, y)) + 
  geom_text(aes(label = family, family = family))

It’s trickier to include a system font on a plot because text drawing is done differently by each graphics device (GD). There are five GDs in common use (png(), pdf(), on screen devices for Windows, Mac and Linux), so to have a font work everywhere you need to configure five devices in five different ways. Two packages simplify the quandary a bit:

Both approaches have pros and cons, so you will to need to try both of them and see which works best for your needs.

Font face

df <- data.frame(x = 1:4, fontface = c("plain", "bold", "italic", "bold.italic"))
ggplot(df, aes(1, x)) + 
  geom_text(aes(label = fontface, fontface = fontface))

Font size

The size of text is measured in mm. This is unusual, but makes the size of text consistent with the size of lines and points. Typically you specify font size using points (or pt for short), where 1 pt = 0.35mm. ggplot2 provides this conversion factor in the variable .pt, so if you want to draw 12pt text, set size = 12 / .pt.


Horizontal and vertical justification have the same parameterisation, either a string (“top”, “middle”, “bottom”, “left”, “center”, “right”) or a number between 0 and 1:

just <- expand.grid(hjust = c(0, 0.5, 1), vjust = c(0, 0.5, 1))
just$label <- paste0(just$hjust, ", ", just$vjust)

ggplot(just, aes(hjust, vjust)) +
  geom_point(colour = "grey70", size = 5) + 
  geom_text(aes(label = label, hjust = hjust, vjust = vjust))

Note that you can use numbers outside the range (0, 1), but it’s not recommended.