2026.10.4
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Truncate text to a length: truncate

The truncate filter shortens a string to a specified maximum length and appends an end marker (by default ...) if the string was truncated. By default, it tries to break at a word boundary so words are not cut in half. This is useful when you need to limit the length of text for display in notifications, dashboard cards, or other contexts with limited space. For example, a sensorSensors return information about a thing, for instance the level of water in a tank. [Learn more] that provides a long description or error message can be truncated to a manageable length so it does not overflow your display.

Usage

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

As a filter 
{{ "This is a very long string that should be truncated" | truncate(20) }}
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".) 
This is a very...

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.
truncate(
    value: str,
    length: int = 255,
    killwords: bool = False,
    end: str = "...",
    leeway: int = 5,
) -> str

Function parameters

The following parameters can be provided to this function.

value string Required

The string to truncate.

length integer (Optional, default: 255)

The maximum length of the output string, including the end marker. Defaults to 255.

killwords boolean (Optional, default: false)

If true, words may be cut in half at the exact length. If false (the default), the string is truncated at the last word boundary before the length limit.

end string (Optional, default: “…”)

The string to append when the text is truncated. Defaults to ....

leeway integer (Optional, default: 5)

If the string is only this many characters longer than the length, it is not truncated. Defaults to 5.

Cutting at exact length

Set killwords to true to truncate at the exact character position, even if it is in the middle of a word.

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]: Cut at exact length 
{{ "Hello beautiful world" | truncate(12, true) }}
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".) 
Hello bea...

Custom end marker

Use a different end marker instead of the default ellipsis.

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]: Custom end marker 
{{ "A very long status message here" | truncate(20, end=" [more]") }}
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".) 
A very long [more]

Good to know

  • The length limit includes the end marker. Truncating to 20 characters with the default ... gives you 17 characters of text plus the three-dot ending.
  • Strings within leeway characters of the limit are returned unchanged. Set leeway=0 if you want a strict cutoff every time.

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.

Shorten a notification message

Truncate a long sensor message so it fits in a mobile notification.

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] 
{{ states("sensor.error_log") | truncate(80) }}
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".) 
Connection timed out while attempting to reach the remote server.
Please check...

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: