diff --git a/doc/classes/ProjectSettings.xml b/doc/classes/ProjectSettings.xml
index b42a10b13b..3da403c681 100644
--- a/doc/classes/ProjectSettings.xml
+++ b/doc/classes/ProjectSettings.xml
@@ -762,7 +762,7 @@
 			If [code]true[/code], performs a previous depth pass before rendering materials. This increases performance in scenes with high overdraw, when complex materials and lighting are used.
 		</member>
 		<member name="rendering/quality/directional_shadow/size" type="int" setter="" getter="" default="4096">
-			The directional shadow's size in pixels. Higher values will result in sharper shadows, at the cost of performance.
+			The directional shadow's size in pixels. Higher values will result in sharper shadows, at the cost of performance. The value will be rounded up to the nearest power of 2.
 		</member>
 		<member name="rendering/quality/directional_shadow/size.mobile" type="int" setter="" getter="" default="2048">
 		</member>
diff --git a/doc/classes/Viewport.xml b/doc/classes/Viewport.xml
index 117c4835eb..9bc46881f9 100644
--- a/doc/classes/Viewport.xml
+++ b/doc/classes/Viewport.xml
@@ -281,7 +281,8 @@
 			The subdivision amount of fourth quadrant on shadow atlas.
 		</member>
 		<member name="shadow_atlas_size" type="int" setter="set_shadow_atlas_size" getter="get_shadow_atlas_size" default="0">
-			The resolution of shadow atlas. Both width and height is equal to one value.
+			The shadow atlas' resolution (used for omni and spot lights). The value will be rounded up to the nearest power of 2.
+			[b]Note:[/b] If this is set to 0, shadows won't be visible. Since user-created viewports default to a value of 0, this value must be set above 0 manually.
 		</member>
 		<member name="size" type="Vector2" setter="set_size" getter="get_size" default="Vector2( 0, 0 )">
 			The width and height of viewport.
diff --git a/doc/classes/VisualServer.xml b/doc/classes/VisualServer.xml
index 5e054ce7ce..e2fc10e44a 100644
--- a/doc/classes/VisualServer.xml
+++ b/doc/classes/VisualServer.xml
@@ -3855,7 +3855,7 @@
 			<argument index="1" name="size" type="int">
 			</argument>
 			<description>
-				Sets the size of the shadow atlas's images.
+				Sets the size of the shadow atlas's images (used for omni and spot lights). The value will be rounded up to the nearest power of 2.
 			</description>
 		</method>
 		<method name="viewport_set_size">