2026.4.1
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Set a default value: default

The default filter returns a fallback value when the variable it is applied to is undefined. If the optional boolean parameter is set to true, it also replaces values that are falsy (empty strings, 0, false, none, and empty collections). This is one of the most commonly used template filters.

In Home Assistant templates, you frequently work with variables that may or may not exist depending on the context. For instance, triggerA trigger is a set of values or conditions of a platform that are defined to cause an automation to run. [Learn more] variables are only available when the automationAutomations in Home Assistant allow you to automatically respond to things that happen in and around your home. [Learn more] actually fires, and custom variables from {% set %} blocks may be conditionally defined. The default filter lets you write robust templates that always produce a usable value, even when some inputs are missing or empty.

Usage

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

As a filter 
{{ my_variable | default("fallback") }}
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".) 
fallback

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.

value | default(
    default_value: Any = "",
    boolean: bool = false,
) -> Any

Function parameters

The following parameters can be provided to this filter.

default_value any (Optional, default: “”)

The value to return if the input is undefined (or falsy, when boolean is true). Defaults to an empty string.

boolean boolean (Optional, default: false)

If true, the filter also replaces falsy values (false, 0, none, empty strings, and empty collections) with the default. If false (the default), only undefined variables are replaced.

Handling undefined variables

When a variable has not been defined, the default filter returns the fallback value instead of raising an error.

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]: Undefined variable gets fallback 
{{ undefined_var | default("no value") }}
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".) 
no value

Replacing falsy values with boolean mode

When boolean is set to true, the filter also replaces empty strings, 0, false, none, and empty lists.

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]: Empty string replaced in boolean mode 
{{ "" | default("empty!", 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".) 
empty!
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]: Zero replaced in boolean mode 
{{ 0 | default(42, true) }}
Result (integerA whole number without decimal places, like 1, 42, or -5. Used for counts, indices, and whole values.) 
42

Good to know

  • Without boolean=true, the default only kicks in for undefined variables. None, empty strings, and 0 pass through unchanged.
  • The default value for default_value is an empty string, not None.
  • This does not catch unavailable or unknown entity states, since those are defined strings. Combine with has_value or float for those cases.

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.

Safe access to trigger data

TriggerA trigger is a set of values or conditions of a platform that are defined to cause an automation to run. [Learn more] variables are only available when the automationAutomations in Home Assistant allow you to automatically respond to things that happen in and around your home. [Learn more] fires. Use default to provide a fallback when testing templates outside an automation context.

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]: Safely access trigger state 
{{ trigger.to_state.state | default("unknown") }}
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".) 
unknown

Provide a default sensor value

When a sensorSensors return information about a thing, for instance the level of water in a tank. [Learn more] might not have a specific attribute, provide a sensible default.

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] 
{{
  state_attr("climate.living_room", "preset_mode")
  | default("none")
}}
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".) 
comfort

Chain with other filters

The default filter is often combined with float or int to ensure calculations do not fail.

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.temperature") | default("0") | float(0) + 5 }}
Result (floatA number that can have decimal places, like 21.5 or 3.14. Used for temperatures, percentages, and other measurements that need precision.) 
26.5

Use in an automation action

Set a notification message with a fallback greeting when the name is not set.

ActionActions are used in several places in Home Assistant. As part of a script or automation, actions define what is going to happen once a trigger is activated. In scripts, an action is called *sequence*. [Learn more] 
action:
  - action: notify.mobile
    data:
      message: >
        Hello {{ states("input_text.user_name") | default("friend") }}!

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: