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Round a number: round

The round filter rounds a numeric value to a specified number of decimal places. It is a Home Assistant override of the standard round filter that adds support for a default parameter and the half rounding method. When rounding to zero decimals, it returns an integer instead of a float.

Rounding is essential whenever you display sensorSensors return information about a thing, for instance the level of water in a tank. [Learn more] values on a dashboard or in a notification. A temperature of 21.456789 is not useful on a dashboard; 21.5 is much better. Similarly, you might want to round energy costs to two decimal places, or display a percentage as a whole number. The round filter supports four rounding methods to cover different use cases, from standard rounding to always rounding up or down.

Usage

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

As a filter

{{ states("sensor.temperature") | float(0) | round(1) }}

Result (float)

21.5

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 = 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.

round(
    value: Any,
    precision: int = 0,
    method: str = "common",
    default: Any,
) -> float | int | Any

Function parameters

The following parameters can be provided to this filter.

value any Required

The value to round. Must be a number or a string that can be converted to a float.

precision integer (Optional, default: 0)

The number of decimal places to round to. Defaults to 0, which returns an integer.

method string (Optional, default: “common”)

The rounding method to use. One of common, ceil, floor, or half. Defaults to common.

default any (Optional)

The value to return if the conversion fails, such as 0. If you leave out default and the conversion fails, round raises an error and the template fails.

Rounding methods

The round filter supports four rounding methods:

Common (default)

The default method uses Python’s built-in rounding, which follows the “round half to even” (banker’s rounding) strategy. Values exactly halfway between two numbers are rounded to the nearest even number.

Template: Round to 1 decimal

{{ 21.456 | round(1) }}

Result (float)

21.5

Template: Banker's rounding: 2.5 rounds to even

{{ 2.5 | round(0) }}

Result (integer)

Template: Values above the halfway point round up

{{ 2.7 | round(0) }}

Result (integer)

Template: Banker's rounding: 3.5 rounds up to the even 4

{{ 3.5 | round(0) }}

Result (integer)

Ceil (always round up)

Always rounds up to the next value at the given precision.

Template: Always round up

{{ 21.1 | round(0, "ceil") }}

Result (integer)

Floor (always round down)

Always rounds down to the previous value at the given precision.

Template: Always round down

{{ 21.9 | round(0, "floor") }}

Result (integer)

Half (round to nearest 0.5)

Rounds the value to the nearest 0.5 increment. This is useful for thermostats and other devicesA device is a model representing a physical or logical unit that contains entities. that operate in half-degree steps.

Template

{{ 21.3 | round(0, "half") }}

Result (float)

21.5

Good to know

The default common method uses banker’s rounding, where 0.5 rounds to the nearest even number. So 2.5 | round gives 2, not 3.
With precision=0 (the default), the result is an integer. With a nonzero precision, the result is a float.
The half method rounds to the nearest 0.5 rather than the nearest whole number.
For example, 2.7 rounds to 3 with common and ceil, and to 2 with floor.
With half, set a precision of 1 or higher to keep the .5: 2.7 | round(1, ‘half’) gives 2.5. At precision 0, the result is cut to a whole number, so 2.7 | round(0, ‘half’) gives 2

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.

Display a clean temperature value

Round a temperature sensor to one decimal place for display on a dashboard.

Template

{{ states("sensor.outdoor_temperature") | float(0) | round(1) }}

Result (float)

18.3

Round up for resource planning

When calculating how many items you need, always round up so you don’t run short.

Template: Cans of paint needed (each covers 10 sqm)

{{ (states("sensor.paint_area") | float(0) / 10) | round(0, "ceil") }}

Result (integer)

Round a cost to two decimals

Display an energy cost with exactly two decimal places.

Template

{{ (states("sensor.energy_today") | float(0) * 0.25) | round(2) }}

Result (float)

3.47

Set a thermostat to the nearest half degree

Round a calculated target temperature to the nearest 0.5 so it matches what the thermostat accepts.

Action

action:
  - action: climate.set_temperature
    target:
      entity_id: climate.living_room
    data:
      temperature: >
        {{
          states("sensor.desired_temperature")
          | float(20) | round(0, "half")
        }}

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:

Convert to float: float - Converts a value to a floating-point number, with an optional default if conversion fails.
Convert to integer: int - Converts a value to an integer, with an optional default if conversion fails.
Multiply a value: multiply - Multiplies a numeric value by a specified amount, with an optional default if conversion fails.
Add to a value: add - Adds a specified amount to a numeric value, with an optional default if conversion fails.

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