Calendar event started

The Calendar event started trigger fires when a calendar event starts. You can also set up the trigger to fire before or after the start of the event.

Use it to automate actions based on the start of a calendar event.

Using this trigger from the user interface

If you prefer building automations visually, Home Assistant walks you through this trigger step by step. You pick what to watch, tweak a few options, and save. No YAML knowledge required.

To use this trigger in an automation:

1. Go to Settings > Automations & scenes.
2. Open an existing automation, or select Create automation > Create new automation.
3. In the When section, select Add trigger.
4. From the search box, search for and select Calendar event started.
5. Under Targets (see Targets), select Add target and pick what to watch. Select the calendar entity with the event that you want to watch. You can also select a device or a label, for example.
6. Under Offset, you can enter the time from the start of the event when the trigger will fire. If you want the trigger to fire at the starting time of the event, skip this and the next option and select Save.
7. If you entered an offset, under Offset type, select one of the following:
   • Before if you want the trigger to fire before the start of the event.
   • After if you want the trigger to fire after the start of the event.
8. Select Save.

Options in the UI

Using this trigger in YAML

If you work directly in YAML, or you want to know exactly what Home Assistant does under the hood, this section has the technical reference. It lists the field names you use in YAML, their types, and which ones are required.

In YAML, refer to this trigger as calendar.event_started. A basic example looks like this:

trigger: calendar.event_started
target:
  entity_id: calendar.personal
options:
  offset:
    hours: 1
    minutes: 15
    seconds: 5
    days: 1
  offset_type: before

This fires 1 day, 1 hour, 15 minutes and 5 seconds before the start of an event in calendar.personal.

Options in YAML

Targets of the trigger

This trigger requires a target. The target is the object that Home Assistant will watch. You can select a single entityAn 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], a device, an area, a floor, or a label as a target, and Home Assistant will watch every matching calendar entity behind that target.

• Entity: one specific calendar entity, such as calendar.living_room.
• Device: every calendar entity that belongs to a device.
• Area: every calendar entity in a room or area.
• Floor: every calendar entity on a floor.
• Label: every calendar entity that shares a label.

You can also select different target types in one trigger. For example, you can add a specific entity and an area as targets in the same trigger to monitor both of them at once.

Good to know

• Note that calendars are read once every 15 minutes. When testing, make sure you do not plan events less than 15 minutes away from the current time, or your triggerA trigger is a set of values or conditions of a platform that are defined to cause an automation to run. [Learn more] might not fire.
• You can also create an automation based on the state of a calendar entityAn 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].
• A calendar trigger should not generally use automation mode single to ensure the trigger can fire when multiple events start at the same time. For example, use queued or parallel instead.
• In YAML, you can also set up other variables for calendar triggers. See Automation Trigger Variables: Calendar to check the available trigger data.

Try it yourself

Ready to test this? Go to Settings > Automations & scenes, create a new automation, and add this trigger. Save the automation, then change the state of the targeted entity to watch the trigger fire on your actual 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 trigger fires in automations and scripts. Copy any example and adapt it to your setup.

Automation: send notification when a calendar event starts

For the calendar entity calendar.my_calendar, at the start of any calendar event, this automation sends a notification that is visible in the notification panel of Home Assistant. This automation allows the start of multiple events at the same time.

• Trigger: Calendar event started
• Action: Send a persistent notification

alias: "Calendar notification"
triggers:
  - trigger: calendar.event_started
    target:
      entity_id: calendar.my_calendar
actions:
  - action: notify.persistent_notification
    data:
      message: Event started!

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with the trigger you’re using and what you expected to happen, or share on our subreddit /r/homeassistant.

Related triggers

These triggers work well alongside this one:

• Calendar event ended: Triggers when a calendar event ends.