How to set font size of Matplotlib axis Legend?

Question

I have a code like this:

import matplotlib.pyplot as plt
from matplotlib.pyplot import *
from matplotlib.font_manager import FontProperties

fontP = FontProperties()
fontP.set_size('xx-small')
fig=plt.figure()
ax1=fig.add_subplot(111)
plot([1,2,3], label="test1")
ax1.legend(loc=0, ncol=1, bbox_to_anchor=(0, 0, 1, 1),
           prop = fontP,fancybox=True,shadow=False,title='LEGEND')
plt.show()

legend fontsize

It can be seen in the plot that the setting in Fontsize does not affect the Legend Title font size.

How to set the font size of the legend title to a smaller size?

For an updated (2021), see https://stackoverflow.com/a/67879275/2612410 — Alejo Bernardin, Jun 07 '21 at 22:17

score 103 · Accepted Answer · edited Sep 05 '19 at 06:46

103

This is definitely an old question, but was frustrating me too and none of the other answers changed the legend title fontsize at all, but instead just changed the rest of the text. So after banging my head against the matplotlib documentation for awhile I came up with this.

legend = ax1.legend(loc=0, ncol=1, bbox_to_anchor=(0, 0, 1, 1),
           prop = fontP,fancybox=True,shadow=False,title='LEGEND')

plt.setp(legend.get_title(),fontsize='xx-small')

As of Matplotlib 3.0.3, you can also set it globally with

plt.rcParams['legend.title_fontsize'] = 'xx-small'

edited Sep 05 '19 at 06:46

Andy Jones

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answered Jun 13 '13 at 17:34

nothilaryy

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`title_fontsize` is now an argument you can pass to `legend(...)`, but your answer made it discoverable for me, so thanks! – Davidmh Jan 30 '23 at 13:24

DougR · Answer 2 · 2015-12-04T12:14:38.530

45

Here is how to change the fontsize of the legend list and/or legend title:

legend=plt.legend(list,loc=(1.05,0.05), title=r'$\bf{Title}$') #Legend: list, location, Title (in bold)
legend.get_title().set_fontsize('6') #legend 'Title' fontsize
plt.setp(plt.gca().get_legend().get_texts(), fontsize='12') #legend 'list' fontsize

edited Dec 04 '15 at 12:14

answered Jan 24 '13 at 10:45

DougR

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Can you please help me in merging the code piece you have proposed with mine? I'm seeing some errors when I add this piece to the code I have. Specifically: Traceback (most recent call last): in legend=plt.legend(list,loc=(1.05,0.05), title=r'$\bf{Title}$') #Legend: list, location, Title (in bold) File "C:\Python26\Lib\site-packages\matplotlib\pyplot.py", line 2800, in legend ret = gca().legend(*args, **kwargs) File "C:\Python26\Lib\site-packages\matplotlib\axes.py", line 4494, in legend labels)] TypeError: zip argument #2 must support iteration – Tapajit Dey Feb 06 '13 at 12:15
I've noticed these commands do not work in Spyder using the IPython console but work well in a standard python (v2.7) console. In IPython it gives 'NameError: name 'gca' is not defined' . – DougR Dec 04 '15 at 11:05

score 35 · Answer 3 · answered May 19 '17 at 15:29

35

Banged my head against it too, here is another more flowing way of doing it:

leg = ax.legend()
leg.set_title('A great legend',prop={'size':14})

answered May 19 '17 at 15:29

Max

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score 34 · Answer 4 · answered Dec 09 '19 at 03:04

Inspired by the current top answer, I found a slightly more natural way to change the fontsizes in the legend. The fontsize argument sets the font size of each of the data labels, and the title_fontsize argument sets the fontsize of the title, if you give the legend a title.

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.plot([0,1,2],[2,1,2],label='test_data (fs=12)')
ax.legend(fontsize=12, title='TITLE (fs=30)',title_fontsize=30)

Gives a figure like this:

this fails if custom lines/patches have been added – Alexander McFarlane May 22 '22 at 01:27 — Alexander McFarlane, May 22 '22 at 01:27

score 14 · Answer 5 · answered Sep 13 '12 at 10:09

14

I don't know how to set it up for an individual plot, but I always do it globally:

plt.rc('legend',**{'fontsize':6})

answered Sep 13 '12 at 10:09

sega_sai

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score 12 · Answer 6 · answered Jun 07 '21 at 22:16

Now in 2021, with matplotlib 3.4.2 you can set your legend fonts with

plt.legend(title="My Title", fontsize=10, title_fontsize=15)

where fontsize is the font size of the items in legend and title_fontsize is the font size of the legend title. More information in matplotlib documentation

score 8 · Answer 7 · answered Jun 23 '16 at 11:27

8

This is the fastest:

plt.legend(loc=2,prop={'size':6})

answered Jun 23 '16 at 11:27

Crococode

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This one doesn't change the title size unfortunately. – Ben Lindsay May 09 '18 at 18:26

score 4 · Answer 8 · answered Sep 13 '12 at 10:18

4

I generally do in this way. Once the plot has been done i do the following

plt.legend(loc=0, numpoints=1)
leg = plt.gca().get_legend()
ltext  = leg.get_texts()
plt.setp(ltext, fontsize='small')

I don't know if this works for you

answered Sep 13 '12 at 10:18

Nicola Vianello

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In ipython notebook, I just do `setp(gca().get_legend().get_texts(), fontsize='small')`. – Ondřej Čertík Jan 04 '13 at 16:28

Bryan Ortiz · Answer 9 · 2022-07-29T22:19:02.307

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The most easy method is using (it served me)

ax.legend(title = "anything", title_fontsize = 8, fontsize = 6)

title_fontsize is useful for changing the fontsize of the title

edited Jul 29 '22 at 22:19

answered Jul 27 '22 at 17:17

Bryan Ortiz

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As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Jul 28 '22 at 16:42

How to set font size of Matplotlib axis Legend?

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