Square root: sqrt

The sqrt template function returns the square root of a value. It wraps Python’s math.sqrt, so the input must be a non-negative number.

This is useful for distance calculations, root-mean-square computations, or any 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] where you need to take the square root of a sensorSensors return information about a thing, for instance the level of water in a tank. [Learn more] value. For example, you could calculate the Euclidean distance between two points or convert power readings.

Usage

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

{{ sqrt(16) }}

4.0

{{ 16 | sqrt }}

4.0

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.

sqrt(
    value: Any,
    default: Any = None,
) -> float

Function parameters

The following parameters can be provided to this function.

Using a default value

If the input value might be negative or non-numeric, provide a default to avoid errors. This keeps your 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] from breaking when a sensor is temporarily unavailable.

{{ sqrt(states("sensor.area") | float(-1), default=0) }}

0

Good to know

• Negative inputs raise an error unless you supply a default.
• The result is always a float, even when the input is a perfect square.

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.

Distance calculation

Calculate the straight-line distance between two points using the Pythagorean theorem.

{% set dx = 3 %}
{% set dy = 4 %}
{{ sqrt(dx**2 + dy**2) }}

5.0

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:

• Logarithm: log - Returns the logarithm of a value with an optional base (default is natural logarithm).

• Euler’s number: e - The mathematical constant e (Euler’s number), approximately 2.71828.

• Pi: pi - The mathematical constant pi, approximately 3.14159.