Is there a way to change the spacing between legend items in ggplot2?

Is there a way to change the spacing between legend items in ggplot2? I currently have

legend.position ="top" 

which automatically produces a horizontal legend. However, the spacing of the items is very close together and I am wondering how to space them farther apart.

ggplot2 v3.0.0 released in July 2018 has working options to modify legend.spacing.x, legend.spacing.y and legend.text.

Update Dec 2021 - to make legend.spacing.y work, you will need to set byrow = TRUE in the corresponding guide_legend. See also this thread. Example below.

Example: Increase horizontal spacing between legend keys

library(ggplot2)

ggplot(mtcars, aes(factor(cyl), fill = factor(cyl))) + 
  geom_bar() +
  coord_flip() +
  scale_fill_brewer("Cyl", palette = "Dark2") +
  theme_minimal(base_size = 14) +
  theme(legend.position = 'top', 
        legend.spacing.x = unit(1.0, 'cm'))

Note: If you only want to expand the spacing to the right of the legend text, use stringr::str_pad()

Example: Increase vertical spacing (mind byrow = TRUE)

library(ggplot2)

ggplot(mtcars, aes(y = factor(cyl), fill = factor(cyl))) + 
  geom_bar() +
  theme(legend.spacing.y = unit(1.0, 'cm'))  +
  ## important additional element
  guides(fill = guide_legend(byrow = TRUE))

Example: Move the legend key labels to the bottom and increase vertical spacing

ggplot(mtcars, aes(factor(cyl), fill = factor(cyl))) + 
  geom_bar() +
  coord_flip() +
  scale_fill_brewer("Cyl", palette = "Dark2") +
  theme_minimal(base_size = 14) +
  theme(legend.position = 'top', 
        legend.spacing.x = unit(1.0, 'cm'),
        legend.text = element_text(margin = margin(t = 10))) +
  guides(fill = guide_legend(title = "Cyl",
                             label.position = "bottom",
                             title.position = "left", title.vjust = 1)) 

Example: for scale_fill_xxx & guide_colorbar

ggplot(mtcars, aes(mpg, wt)) +
  geom_point(aes(fill = hp), pch = I(21), size = 5)+
  scale_fill_viridis_c(guide = FALSE) +
  theme_classic(base_size = 14) +
  theme(legend.position = 'top', 
        legend.spacing.x = unit(0.5, 'cm'),
        legend.text = element_text(margin = margin(t = 10))) +
  guides(fill = guide_colorbar(title = "HP",
                               label.position = "bottom",
                               title.position = "left", title.vjust = 1,
                               # draw border around the legend
                               frame.colour = "black",
                               barwidth = 15,
                               barheight = 1.5)) 

The below is obsolete, but is left for curious people.

For vertical legends, settinglegend.key.size only increases the size of the legend keys, not the vertical space between them

ggplot(mtcars) +
  aes(x = cyl, fill = factor(cyl)) +
  geom_bar() +
  scale_fill_brewer("Cyl", palette = "Dark2") +
  theme_minimal(base_size = 14) +
  theme(legend.key.size = unit(1, "cm"))

In order to increase the distance between legend keys, modification of the legend-draw.r function is needed. See this issue for more info

# function to increase vertical spacing between legend keys
# @clauswilke
draw_key_polygon3 <- function(data, params, size) {
  lwd <- min(data$size, min(size) / 4)
  
  grid::rectGrob(
    width = grid::unit(0.6, "npc"),
    height = grid::unit(0.6, "npc"),
    gp = grid::gpar(
      col = data$colour,
      fill = alpha(data$fill, data$alpha),
      lty = data$linetype,
      lwd = lwd * .pt,
      linejoin = "mitre"
    ))
}

### this step is not needed anymore per tjebo's comment below
### see also: https://ggplot2.tidyverse.org/reference/draw_key.html
# register new key drawing function, 
# the effect is global & persistent throughout the R session
# GeomBar$draw_key = draw_key_polygon3

ggplot(mtcars) +
  aes(x = cyl, fill = factor(cyl)) +
  geom_bar(key_glyph = "polygon3") +
  scale_fill_brewer("Cyl", palette = "Dark2") +
  theme_minimal(base_size = 14) +
  theme(legend.key = element_rect(color = NA, fill = NA),
        legend.key.size = unit(1.5, "cm")) +
  theme(legend.title.align = 0.5)

I think the best option is to use guide_legend within guides:

p + guides(fill=guide_legend(
                 keywidth=0.1,
                 keyheight=0.1,
                 default.unit="inch")
      )

Note the use of default.unit , no need to load grid package.

A simple fix that I use to add space in horizontal legends, simply add spaces in the labels (see extract below):

  scale_fill_manual(values=c("red","blue","white"),
                    labels=c("Label of category 1          ",
                             "Label of category 2          ",
                             "Label of category 3"))

To add spacing between entries in a legend, adjust the margins of the theme element legend.text.

To add 30pt of space to the right of each legend label (may be useful for a horizontal legend):

p + theme(legend.text = element_text(
    margin = margin(r = 30, unit = "pt")))

To add 30pt of space to the left of each legend label (may be useful for a vertical legend):

p + theme(legend.text = element_text(
    margin = margin(l = 30, unit = "pt")))

for a ggplot2 object p. The keywords are legend.text and margin.

[Note about edit: When this answer was first posted, there was a bug. The bug has now been fixed]

Now that opts is deprecated in ggplot2 package, function theme should be used instead:

library(grid) # for unit()
... + theme(legend.key.height=unit(3,"line"))
... + theme(legend.key.width=unit(3,"line"))