matplotlib · timhoffm · Jul 22, 2025 · Jul 21, 2025 · Jul 22, 2025
diff --git a/doc/devel/coding_guide.rst b/doc/devel/coding_guide.rst
@@ -215,7 +215,7 @@ If an end-user of Matplotlib sets up `logging` to display at levels more
 verbose than ``logging.WARNING`` in their code with the Matplotlib-provided
 helper::
 
-  plt.set_loglevel("debug")
+  plt.set_loglevel("DEBUG")
 
 or manually with ::
 

diff --git a/doc/devel/troubleshooting.rst b/doc/devel/troubleshooting.rst
@@ -23,7 +23,7 @@ mode::
     git clean -xfd
     git pull
     python -m pip install -v . > build.out
-    python -c "from pylab import *; set_loglevel('debug'); plot(); show()" > run.out
+    python -c "from pylab import *; set_loglevel('DEBUG'); plot(); show()" > run.out
 
 and post :file:`build.out` and :file:`run.out` to the `matplotlib-devel
 <https://mail.python.org/mailman/listinfo/matplotlib-devel>`_

diff --git a/doc/install/index.rst b/doc/install/index.rst
@@ -179,7 +179,7 @@ development environment such as :program:`IDLE` which add additional
 complexities. Open up a UNIX shell or a DOS command prompt and run, for
 example::
 
-   python -c "from pylab import *; set_loglevel('debug'); plot(); show()"
+   python -c "from pylab import *; set_loglevel('DEBUG'); plot(); show()"
 
 This will give you additional information about which backends Matplotlib is
 loading, version information, and more. At this point you might want to make

diff --git a/doc/users/faq.rst b/doc/users/faq.rst
@@ -367,7 +367,7 @@ provide the following information in your e-mail to the `mailing list
 * Matplotlib provides debugging information through the `logging` library, and
   a helper function to set the logging level: one can call ::
 
-    plt.set_loglevel("info")  # or "debug" for more info
+    plt.set_loglevel("INFO")  # or "DEBUG" for more info
 
   to obtain this debugging information.
 

diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -292,17 +292,21 @@ def set_loglevel(level):
     - set the root logger handler's level, creating the handler
       if it does not exist yet
 
-    Typically, one should call ``set_loglevel("info")`` or
-    ``set_loglevel("debug")`` to get additional debugging information.
+    Typically, one should call ``set_loglevel("INFO")`` or
+    ``set_loglevel("DEBUG")`` to get additional debugging information.
 
     Users or applications that are installing their own logging handlers
     may want to directly manipulate ``logging.getLogger('matplotlib')`` rather
     than use this function.
 
     Parameters
     ----------
-    level : {"notset", "debug", "info", "warning", "error", "critical"}
-        The log level of the handler.
+    level : {"NOTSET", "DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"}
+        The log level as defined in `Python logging levels
+        <https://docs.python.org/3/library/logging.html#logging-levels>`__.
+
+        For backwards compatibility, the levels are case-insensitive, but
+        the capitalized version is preferred in analogy to `logging.Logger.setLevel`.
 
     Notes
     -----

diff --git a/lib/matplotlib/typing.py b/lib/matplotlib/typing.py
@@ -93,7 +93,7 @@
 CapStyleType: TypeAlias = CapStyle | Literal["butt", "projecting", "round"]
 """Line cap styles. See :doc:`/gallery/lines_bars_and_markers/capstyle`."""
 
-LogLevel: TypeAlias = Literal["notset", "debug", "info", "warning", "error", "critical"]
+LogLevel: TypeAlias = Literal["NOTSET", "DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]
 """Literal type for valid logging levels accepted by `set_loglevel()`."""
 
 CoordsBaseType = Union[