Get length of a collection: length

The length filter returns the number of items in a collection. For lists, it returns the number of elements. For strings, it returns the number of characters. For dictionaries, it returns the number of keys. It is also available under the alias count.

This is one of the most commonly used filters when working with 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] collections. You will frequently use it to count how many lights are on, how many doors are open, how many sensorsSensors return information about a thing, for instance the level of water in a tank. [Learn more] are above a threshold, or how many devicesA device is a model representing a physical or logical unit that contains entities. are in a particular area. It typically appears at the end of a filter chain after select, selectattr, or expand.

Usage

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

{{ [1, 2, 3, 4, 5] | length }}

5

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 default are required.

length(
    value: Sized,
) -> int

Function parameters

The following parameters can be provided to this filter.

The count alias

The count filter is an alias for length. They behave identically.

{{ ["a", "b", "c"] | count }}

3

Good to know

• Cannot count generators directly. Add | list after select, map, or selectattr first.
• For strings, it counts characters, not words or bytes.

Try it yourself

Ready to test this? Open Developer 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.

Count how many lights are on

Count the number of lights currently in the “on” state.

{{
  expand("group.all_lights")
  | selectattr("state", "eq", "on")
  | list
  | length
}}

5

Count open doors

Count how many door sensors report an “on” (open) state.

{{
  expand("group.door_sensors")
  | selectattr("state", "eq", "on")
  | list
  | count
}}

2

Get the number of attributes on an entity

Count how many attributes a particular entity has.

{{ states.sensor.weather.attributes | length }}

8

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.

Related template functions

These functions work well alongside this one:

• Get first item: first - Returns the first item of a list or the first character of a string.

• Get last item: last - Returns the last item of a list or the last character of a string.

• Filter items by test: select - Filters a list, keeping only items that pass a given test.