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Convert to datetime: as_datetime

The as_datetime template function converts a date/time string or a UNIX timestamp into a datetimeA value representing a specific moment in time, including the date, time, and time zone. For example, 2026-04-05 14:30:00+00:00. Used for timestamps, scheduling, and time-based calculations. object. Give it an ISO 8601 formatted string like “2024-03-15T14:30:00” or a numeric timestamp, and it returns a proper datetime you can work with in your templates.

Many sensorsSensors return information about a thing, for instance the level of water in a tank. [Learn more] and integrationsIntegrations connect and integrate Home Assistant with your devices, services, and more. [Learn more] provide dates and times as plain text strings or UNIX timestamps. To compare those values with now, calculate time differences, or format them for display, you first need to turn them into datetime objects. as_datetime handles this conversion for you. It accepts ISO 8601 formatted strings (the most common format in Home Assistant) as well as numeric UNIX timestamps.

Usage

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

As a function

As a filter

Template

{{ as_datetime("2024-03-15T14:30:00+01:00") }}

Result (datetime)

2024-03-15 14:30:00+01:00

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.

as_datetime(
    value: str | int | float,
    default: Any,
) -> datetime | Any

Function parameters

The following parameters can be provided to this function.

value string | float Required

The value to convert to a datetime. Can be an ISO 8601 formatted string or a numeric UNIX timestamp.

default any (Optional)

The value to return if the conversion fails, such as "unknown". If you leave out default and the input is invalid text, as_datetime returns None. For other invalid input, as_datetime raises an error and the template fails.

Converting from a UNIX timestamp

You can also convert a numeric UNIX timestamp (seconds since January 1, 1970) into a datetime object.

Template

{{ as_datetime(1710510600) }}

Result (datetime)

2024-03-15 13:50:00+00:00

Using a default value

If the input string might be invalid, provide a default value to use instead of None.

Template

{{ as_datetime("not a date", default="unknown") }}

Result (string)

unknown

Good to know

A string without a time zone gives a datetime without a time zone. To compare it with now, add | as_local to treat it as local time. Strings with an offset or Z suffix keep their time zone.
UNIX timestamps are interpreted in UTC, so chain with as_local if you need local time.
Without a default, invalid text returns None. Other invalid input, such as a list, raises an error.

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.

Convert a sensor value to a datetime

Many sensors store dates as strings. Convert them to datetime objects to perform comparisons or calculations.

Template

{{ as_datetime(states("sensor.next_appointment")) }}

Result (datetime)

2024-03-15 14:30:00+01:00

Calculate time until a future event

Convert a date string from a sensor and calculate how many hours remain until that event.

Template

{% set event = as_datetime(states("sensor.next_appointment")) %}
{{ ((event - now()).total_seconds() / 3600) | round(1) }}

Result (float)

3.5

Chain with as_local

Convert a UTC datetime string to your local time zone by chaining as_datetime with as_local.

Template

{{ as_datetime("2024-03-15T13:30:00+00:00") | as_local }}

Result (datetime)

2024-03-15 14:30:00+01:00

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 UNIX timestamp: as_timestamp - Converts a datetime object or string to a UNIX timestamp.
Convert to local time zone: as_local - Converts a datetime object to your local time zone.
Parse duration string: as_timedelta - Parses an ISO 8601 duration string into a timedelta object.
Parse a time string: strptime - Parses a time string with a specified format into a datetime object.
Current local date and time: now - Returns the current date and time in your local time zone.

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