Light brightness

The Light brightness condition passes when a light entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more]‘s brightness meets a threshold you set. You can check that the brightness is above, below, or within a specific range. Brightness is measured as a percentage of full brightness, from 0 to 100. Use it to gate an automation based on how bright the light currently is, not just whether it’s on or off.

When you target more than one light, the condition’s Condition passes if option controls how the check combines. You can require any targeted light’s brightness to match, or demand that all of them do.

Using this condition from the user interface

If you prefer building automations visually, Home Assistant walks you through this condition step by step. You pick what to check, tweak a few options, and save. No YAML knowledge required.

To use Light brightness in an automation:

1. Go to Settings > Automations & scenes.
2. Open an existing automation, or select Create automation > Create new automation.
3. In the And if section, select Add condition.
4. Select what you want to check. Under By target (see Targets), pick the area your light is in (like your living room or bedroom). You can also select a device, a specific entity, or a label.
5. From the conditions shown for that target, select Light brightness.
6. Under Threshold type, set the level the condition checks against:
   1. Pick whether the reading must be Above, Below, In range, or Outside range of the threshold.
   2. Select Number or Entity:
      • Number: Enter a fixed percentage directly, for example 50 for 50%. For In range or Outside range, enter both a lower and upper bound.
      • Entity: Use a sensor entity or a number helper entity as the threshold:
        • Number helper: You can adjust the threshold value without editing the automation. The sensor reading is compared against the number helper’s current value.
        • Sensor: Its current reading becomes the threshold and updates automatically as the sensor changes.
        • For In range or Outside range, you need two entities: one for the lower bound and one for the upper bound (for example, two separate number helpers).
        • If you don’t have a number helper, you can create one by selecting Create a new number helper.
7. Under Condition passes if (see Behavior), pick Any or All.
8. Select Save.

Options in the UI

Using this condition in YAML

If you work directly in YAML, or you want to know exactly what Home Assistant does under the hood, this section has the technical reference. It lists the field names you use in YAML, their types, and which ones are required.

In YAML, refer to this condition as light.is_brightness. A basic example looks like this:

condition: light.is_brightness
target:
  entity_id: light.living_room
options:
  threshold:
    type: above
    value:
      number: 50
  behavior: any

This passes when the living room light’s brightness is above 50%.

Options in YAML

Targets of the condition

This condition requires a target. The target is the object that Home Assistant will check. You can point the condition at a single entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more], a device, an area, a floor, or a label, and Home Assistant will evaluate every matching light entity behind that target.

• Entity: one specific light entity, such as light.living_room.
• Device: every light entity that belongs to a device.
• Area: every light entity in a room or area.
• Floor: every light entity on a floor.
• Label: every light entity that shares a label.

You can also select different target types in one condition. For example, you can add a specific entity and an area as targets in the same condition to check both of them at once.

To learn which entities Home Assistant includes for a device, area, floor, or label, and how it handles several entities, refer to Automation targets.

Behavior with multiple targets

When you target more than one entity (or select an area, floor, or label that contains several), the Condition passes if option controls how the results combine:

• Any (default): the condition passes if at least one of the targeted entities matches. For example, if you check three smoke sensors and only one of them detects smoke, the condition still passes. This is useful for questions like “is there smoke anywhere in the house?”
• All: the condition passes only when every targeted entity matches. For example, if you check the same three smoke sensors, the condition passes only once all three report cleared. This is useful for “is the entire house safe now?” checks, so your automation does not send an all-clear while one room still has a reading.

Good to know

• A light that is off has no brightness value, so it never passes this condition, not even with Below. To check whether a light is off, use Light is off instead.
• If you use an entity as the threshold, it must report its value in percent (%). An entity with a different unit, or no unit, is ignored and the condition does not pass.
• Lights that are unavailable or unknown are skipped. With Any, the condition passes if at least one of the other targeted lights matches. With All, it passes if all the other targeted lights match. If all targeted lights are unavailable or unknown, All passes and Any fails.
• Pair with Light brightness crossed threshold as a matching trigger when you need the automation to run the moment the brightness crosses that line.

Try it yourself

Ready to test this? Go to Settings > Automations & scenes, open an automation, and add this condition. Trigger the automation with and without the condition met, and watch whether it continues or stops.

More examples

Real scenarios where this condition gates an automation. Copy any example and adapt it to your setup. In the visual editor, select the UI options listed in the example or paste the YAML code.

Automation: only start the movie scene if the room is dim enough

When the movie-night button is pressed, only start the movie scene if the living room light is dimmer than 40%. If the room is still bright, prompt for manual dimming first.

• Trigger: State changed: Movie night button pressed
• Condition: Light brightness
  • Target: Living room light
  • Threshold type: Below 40%
  • Condition passes if: Any
• Action: Activate scene
  • Target: Movie night

alias: "Movie scene only if dim"
triggers:
  - trigger: state
    entity_id: input_button.movie_night
conditions:
  - condition: light.is_brightness
    target:
      entity_id: light.living_room
    options:
      threshold:
        type: below
        value:
          number: 40
      behavior: any
actions:
  - action: scene.turn_on
    target:
      entity_id: scene.movie_night

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with the condition you’re using and what you expected to happen, or share on our subreddit /r/homeassistant.

Related conditions

Explore related conditions:

• Light is on: Tests if one or more lights are on.

• Light is off: Tests if one or more lights are off.