2026.4.1
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Test less than: lt

The lt test checks whether a value is strictly less than another value. It is also available under the aliases lessthan and <. When used with is, it reads naturally: value is lt(other).

While you can always use < directly in conditions, the lt test is essential when working with selectattr, select, and similar filters that require a test name as a string. This lets you filter collections by comparing values to an upper limit without writing explicit loops.

Usage

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

As a test 
{% if 3 is lt(5) %}
  Less than
{% endif %}
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".) 
Less than

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.

lt(
    value: Any,
    other: Any,
) -> bool

Function parameters

The following parameters can be provided to this function.

value any Required

The value to test. This is the left-hand side of the comparison.

other any Required

The value to compare against.

Aliases

This test can also be used as:

  • lessthan - value is lessthan(other)
  • < - value is <(other)

Using with selectattr

Filter entities below a certain threshold, for example to find low battery devices.

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]: Low battery devices 
{{
  states.sensor
  | selectattr("attributes.battery_level", "lt", 20)
  | map(attribute="name") | list
}}
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].) 
['Remote Control']

Good to know

  • When comparing entity state strings with numbers, convert first or wrap the threshold in quotes. String comparison puts "9" above "10".
  • This is strict. A value equal to the threshold does not pass. Use le for less-or-equal.

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.

Filter values below a limit

Use select to find numbers below a threshold.

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] 
{{ [10, 25, 30, 15, 40] | select("lt", 20) | list }}
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].) 
[10, 15]

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: