EventBridge vs Scheduler.

Two services, easily confused

AWS introduced EventBridge Scheduler as a successor to EventBridge's rule-based scheduling. The original isn't deprecated — both still work — but they have different capabilities.

Cron expression differences

Both use 6-field Quartz-style cron with the year field:

# Both formats: minute hour day-of-month month day-of-week year
cron(0 9 ? * MON-FRI *)   # Weekdays at 9 AM

Same rules: ? required in one day field, L and W supported, day-of-week starts at 1=Sunday.

Timezone in Scheduler

Configure via the ScheduleExpressionTimezone property:

{
  "Name": "morning-report",
  "ScheduleExpression": "cron(0 9 ? * MON-FRI *)",
  "ScheduleExpressionTimezone": "America/New_York",
  "Target": { ... }
}

Now 9 AM means 9 AM Eastern, automatically adjusting for DST.

When to use which

Use EventBridge Rules when:

• You're already on EventBridge for event-driven workflows
• UTC scheduling is fine
• You have fewer than 300 schedules
• You want the free tier (rules are free; only target invocations cost)

Use EventBridge Scheduler when:

• You need timezone-aware schedules (most user-facing apps)
• You need one-time future-dated schedules ("send this email on 2026-12-31")
• You have hundreds or thousands of distinct schedules
• You're starting a new project (Scheduler is the modern path)

Migrating from Rules to Scheduler

The cron expressions are identical, so the schedule itself migrates 1:1. What changes:

• Configuration moves from EventBridge → EventBridge Scheduler in the console
• You'll likely add ScheduleExpressionTimezone
• Targets are configured per-schedule, not via Rules → Targets associations
• You pay per-invocation now (was free for rule scheduling)

For most teams, the timezone support alone is worth the migration.

Written by Murugan Vellaichamy. Suggestions or corrections? Get in touch.