diff --git a/homeassistant/components/light/services.yaml b/homeassistant/components/light/services.yaml
index cdf82e97429ad2..d4985258368b8a 100644
--- a/homeassistant/components/light/services.yaml
+++ b/homeassistant/components/light/services.yaml
@@ -31,10 +31,10 @@ turn_on:
       description: Number between 0..255 indicating level of white.
       example: '250'
     brightness:
-      description: Number between 0..255 indicating brightness.
+      description: Number between 0..255 indicating brightness, where 0 turns the light off, 1 is the minimum brightness and 255 is the maximum brightness supported by the light.
       example: 120
     brightness_pct:
-      description: Number between 0..100 indicating percentage of full brightness.
+      description: Number between 0..100 indicating percentage of full brightness, where 0 turns the light off, 1 is the minimum brightness and 100 is the maximum brightness supported by the light.
       example: 47
     profile:
       description: Name of a light profile to use.