2026.10.4
Home ▸ Template functions

Get a device ID: device_id

The device_id template function returns the deviceA device is a model representing a physical or logical unit that contains entities. ID associated with an 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] ID or a device name. If you pass an entity ID, it looks up which device that entity belongs to. If you pass a device name, it searches for a device with that exact name. It returns None if no matching device is found.

This is the starting point for most device-related template work. Since many device functions require a device ID, you’ll often use device_id to get that ID from something more human-readable. For example, you might know the entity ID of your thermostat sensor but need the device ID to look up the manufacturer or firmware version with device_attr. Or you might want to find all entities on the same device as a particular sensor using device_entities.

Usage

Here’s how to use this template function. Copy any example and adjust it to your setup.

TemplateA template is an automation definition that can include variables for the action or data from the trigger values. This allows automations to generate dynamic actions. [Learn more] 
{{ device_id("sensor.living_room_temperature") }}
Result (stringA piece of text, like a name, message, or entity ID. In templates, wrap strings in quotes, like "living_room" or "lights are on".) 
a1b2c3d4e5f6a1b2c3d4e5f6

Function signature

The signature is a technical summary of this template function. It shows the name of the function, the values (called parameters) it accepts, and what type of data each parameter expects (for example, a piece of text or a number).

Function parameters that have a = with a value after them are optional. If you leave them out, the default value shown is used automatically.

Function parameters without a = are usually required. A few optional parameters have no default value, so the signature shows them without a = as well. To check whether a parameter is required, look at the parameter list below the signature. Each parameter is marked as Required or Optional.

The most common optional parameter without a default value is default. The default parameter sets the value a function returns when the function can’t produce a result, for example, when float gets text that isn’t a number. If you leave out default, there is no fallback value, so most functions raise an error and the template fails. The parameter list of each function says what happens. If you set default, the function returns your value instead.

How to read a signature

Here is the signature of the round filter as an example:

round(
    value: Any,
    precision: int = 0,
    method: str = "common",
    default: Any,
) -> float | int | Any
  • round is the name of the function.
  • Between the parentheses are the parameters. Each parameter has a name, followed by a colon and the type of value the parameter expects. The type only tells you what kind of value to pass. For default: Any, you pass a value of any type, such as 0 or "unknown", not the word Any.
  • = 0 and = "common" are default values. You can leave out precision and method, and round uses these default values.
  • default has no =, but the parameter list marks default as optional. If you leave out default and round gets a value that isn’t a number, round raises an error.
  • -> shows the type of value the function returns.
  • Inside a signature, | means “or”. This function returns a decimal number, a whole number, or the value you passed as default.

round is a filter, so the first parameter, value, is the value before the |. For example, {{ 3.14159 | round(2) }} returns 3.14.

The types you’ll see most often:

  • str: text, such as "hello"
  • int: a whole number, such as 5
  • float: a decimal number, such as 3.14
  • bool: true or false
  • list: a list of values, such as [1, 2, 3]. list[str] is a list of texts.
  • dict: a set of keys and values, such as {"name": "Kitchen"}
  • datetime and timedelta: a date and time, and a duration. For details, refer to Dates and times.
  • None: no value
  • Any: any type of value

Some signatures use special forms:

  • *args means you can pass any number of values, separated by commas. For example, average(1, 2, 3).
  • value | name(...) means the function is a filter. The value before the | is passed to the filter as its first parameter. Some filter signatures, like the round example, show this value as the first parameter between the parentheses instead.
device_id(
    entity_id_or_device_name: str,
) -> str | None

Function parameters

The following parameters can be provided to this function.

entity_id_or_device_name string Required

The entity ID or the name of the device. When using a device name, it matches against the custom name you set first, then falls back to the default device name.

Good to know

  • Returns None when no device matches or when the entity does not belong to a device.
  • Name lookups need an exact match, including capitalization and spaces.
  • When you set a custom device name, that name takes precedence over the default device name.

Try it yourself

Ready to test this? Open Settings > Tools > Template, paste the example into the Template editor, and watch the result update on the right. Edit the values to see how the function adapts to your own entitiesAn 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].

More examples

Real scenarios where this function comes up in automations and templates. Copy any example and adapt it to your setup.

Look up a device ID by device name

You can also pass a device name instead of an entity ID. This is handy when you know the name of the device but not its ID.

TemplateA template is an automation definition that can include variables for the action or data from the trigger values. This allows automations to generate dynamic actions. [Learn more] 
{{ device_id("Living Room Thermostat") }}
Result (stringA piece of text, like a name, message, or entity ID. In templates, wrap strings in quotes, like "living_room" or "lights are on".) 
a1b2c3d4e5f6a1b2c3d4e5f6

Chain with device_entities to find sibling entities

Find all entities that share the same device as a known entity. This is useful when you know one entity on a device and want to discover the rest.

TemplateA template is an automation definition that can include variables for the action or data from the trigger values. This allows automations to generate dynamic actions. [Learn more] 
{{
  device_id("sensor.living_room_temperature")
  | device_entities
}}
Result (listAn ordered collection of values, like a list of entity IDs or a list of numbers. Written with square brackets in templates, for example [1, 2, 3].) 
[
  "sensor.living_room_temperature",
  "sensor.living_room_humidity",
  "binary_sensor.living_room_battery",
]

Get the manufacturer of a device from an entity ID

Combine device_id with device_attr to look up device attributes starting from an entity ID.

TemplateA template is an automation definition that can include variables for the action or data from the trigger values. This allows automations to generate dynamic actions. [Learn more] 
{{
  device_attr(
    device_id("sensor.living_room_temperature"),
    "manufacturer"
  )
}}
Result (stringA piece of text, like a name, message, or entity ID. In templates, wrap strings in quotes, like "living_room" or "lights are on".) 
Aqara

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with your template and expected result, or share on our subreddit /r/homeassistant.

Tip

AI assistants like ChatGPT or Claude can also explain or fix templates when you describe what you want in plain language.

Related template functions

These functions work well alongside this one: