Datetime Offset

Datetime Offset

Applies a time offset to a datetime entity or helper.

Overview

A datetime offset sensor calculates a new datetime by adding or subtracting a time duration from a source datetime.

Configuration

1. Select "Datetime Offset"
2. Configure:
   • Calculation Name: A friendly name
   • Datetime Entity: The source datetime entity
   • Time Offset: Duration to add (e.g., "1 hour") or subtract (e.g., "-30 minutes")
   • Icon: Optional custom icon

Examples

1. Set Alarm 30 Minutes Before Meeting

{
  "type": "datetime_offset",
  "name": "Meeting Reminder Time",
  "datetime_entity": "input_datetime.meeting_time",
  "offset": "-30 minutes"
}

If meeting is at 2:00 PM, sensor shows 1:30 PM

2. Schedule Preparation Time

{
  "type": "datetime_offset",
  "name": "Start Getting Ready",
  "datetime_entity": "input_datetime.work_start",
  "offset": "-1 hour"
}

3. Schedule Post-Event Cleanup

{
  "type": "datetime_offset",
  "name": "Cleanup Start Time",
  "datetime_entity": "input_datetime.party_end",
  "offset": "15 minutes"
}

Offset Format

• Positive: "1 hour" adds time
• Negative: "-30 minutes" subtracts time
• Units: second, minute, hour, day, week

Automation Example

automation:
  - alias: "Remind 30 min before meeting"
    trigger:
      platform: time
      at: sensor.meeting_reminder_time
    action:
      service: notify.mobile_app
      data:
        message: "Meeting starting in 30 minutes!"