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

89

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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@aquirdturtle and Alejo Bernardin have up-to-date answers. The accepted answer is no longer a good answer. – Bogdan Dec 09 '21 at 21:37

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

41

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

31

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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This is the cleanest of all the options as far as I can tell. – Ben Lindsay May 09 '18 at 18:26

score 23 · Answer 4 · answered Dec 09 '19 at 03:04

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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:

answered Dec 09 '19 at 03:04

aquirdturtle

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This should be the top answer – Gene Burinsky Jan 06 '20 at 00:27
this fails if custom lines/patches have been added – Alexander McFarlane May 22 '22 at 01:27

score 15 · Answer 5 · answered Sep 13 '12 at 10:09

15

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 9 · 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 7 · Answer 7 · answered Jun 23 '16 at 11:27

7

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

5

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

How to set font size of Matplotlib axis Legend?

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