2026.10.4
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Human-readable time elapsed: time_since

The time_since template function returns a human-readable string describing how much time has elapsed since a given 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.. Give it a datetime in the past, and it returns something like “2 hours” or “3 days 5 hours” instead of a raw number of seconds.

This is useful whenever you want to display elapsed time in a natural, readable format. For example, showing “last seen 45 minutes ago” on a dashboard, displaying how long a door has been open, or reporting how long ago a sensor last updated. The function only works with datetimes in the past. For future datetimes, use time_until instead. You can control the level of detail with the optional precision parameter, which determines how many time components (years, months, days, hours, minutes, seconds) to include.

Usage

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

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] 
{{ time_since(states.binary_sensor.front_door.last_changed) }}
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".) 
2 hours

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.
time_since(
    value: datetime,
    precision: int = 1,
) -> str

Function parameters

The following parameters can be provided to this function.

value datetime Required

A datetime object representing a point in the past. The function calculates the time elapsed between this datetime and now.

precision integer (Optional, default: 1)

The number of time components to include in the output. A precision of 1 might return “2 hours”, while a precision of 2 might return “2 hours 30 minutes”. Higher precision gives more detail. Use 0 to include every time component that isn’t zero.

Controlling precision

By default, time_since returns only the largest time component. Increase the precision to include more detail.

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] 
{{ time_since(states.binary_sensor.front_door.last_changed, 1) }}
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".) 
2 hours
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] 
{{ time_since(states.binary_sensor.front_door.last_changed, 3) }}
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".) 
2 hours 15 minutes 10 seconds

Good to know

  • Only works with datetimes in the past. A datetime in the future is returned unchanged, without an error. For future datetimes, use time_until instead.
  • The last unit shown is rounded to the nearest whole number. All other units are cut off. For example, 2 hours 45 minutes gives "3 hours" with a precision of 1.
  • Because of this rounding, the result doesn’t carry over to the next unit. For example, 59 minutes 40 seconds gives "60 minutes", not "1 hour".
  • Units that are zero are skipped and don’t count toward the precision. For example, 2 hours and 15 seconds gives "2 hours 15 seconds" with a precision of 2.
  • Durations shorter than half a second return "0 seconds".
  • If the input isn’t a datetime, it’s returned unchanged. This includes none, which as_datetime returns for states like unknown.
  • Datetimes without a time zone are accepted. They’re treated as your local time.

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.

Show how long a door has been open

Display the elapsed time since a door opened on your dashboard.

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] 
{{
  "Open for "
  ~ time_since(states.binary_sensor.front_door.last_changed)
}}
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".) 
Open for 2 hours

Detailed elapsed time in a notification

Send a notificationYou can use notifications to send messages, pictures, and more, to devices. [Learn more] with a more detailed breakdown of elapsed time.

ActionAn action makes Home Assistant do something, for example, turn on a light, send a notification, or activate a scene. Automations and scripts run a list of actions. [Learn more] 
action:
  - action: notify.mobile
    data:
      message: >
        The washing machine has been running for
        {{ time_since(states.sensor.washer_start.last_changed, 2) }}.

Show when something was last seen

Create a “last seen” display for a person tracker.

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] 
{{
  "Last seen "
  ~ time_since(states.person.paulus.last_changed) ~ " ago"
}}
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".) 
Last seen 45 minutes ago

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: