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 linewidth, linetype, linejoin and lineend.

Line type

Line types can be specified with:


Due to a historical error, the unit of linewidth is roughly 0.75 mm. Making it exactly 1 mm would change a very large number of existing plots, so we’re stuck with this mistake.

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 linewidth 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", linewidth = 6) + 
  geom_point(shape = 21, fill = "red") +

A plot showing a 4-by-4 grid of red points, the top 12 points with black outlines. The size of the points increases horizontally. The stroke of the outlines of the points increases vertically. A white diagonal line with a negative slope marks that the 'stroke' versus 'size' trade-off has similar total sizes.


Font family

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))

A plot showing three text labels arranged vertically. The top label is 'sans' and is displayed in a sans-serif font. The middle label is 'serif' and is displayed in a serif font. The bottom label is 'mono' and is displayed in a monospaced font.

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))

A plot showing four text labels arranged vertically. The top label is 'bold.italic' and is displayed in bold and italic. The next three labels are 'italic', 'bold' and 'plain' and are displayed in their respective styles.

Font size

The size of text is measured in mm by default. 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. In geom_text() and geom_label(), you can set size.unit = "pt" to use points instead of millimeters. In addition, ggplot2 provides a conversion factor as the variable .pt, so if you want to draw 12pt text, you can also 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))

A 3-by-3 grid of text on top of points, with horizontal text justification increasing from 0 to 1 on the x-axis and vertical justification increasing from 0 to 1 on the y-axis. The points make it easier to see the relative placement of text.

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