CRON Expressions in Scheduled Apex (with Example)

Automation is at the heart of enterprise software, and Salesforce is not different. Though automation scenarios for many are taken care of by tools such as Flow and Process Builder, there are instances where you want granular control over scheduling and execution this is where Scheduled Apex and Cron Expressions enter the picture.

What Is a Cron Expression?

A Cron Expression is a string of special format that specifies the timing on which a job needs to be executed. It consists of 7 fields within Salesforce and instructs the platform when to invoke a scheduled Apex job.

Cron Expression Syntax

Here’s the format of a cron expression used in Salesforce:

Seconds  Minutes  Hours  Day_of_month  Month  Day_of_week  Year

Allowed Values:

Field	Values
Seconds	0–59
Minutes	0–59
Hours	0–23
Day of Month	1–31
Month	1–12 or JAN–DEC
Day of Week	1–7 or SUN–SAT
Year (optional)	1970–2099

Important: You must use ? in either the Day of Month or Day of Week field to avoid conflicts.

Special Characters Explained

Symbol	Meaning
*	Every value
?	No specific value (used in day-of-month or day-of-week)
–	Range (e.g., MON-FRI)
/	Increment (e.g., 0/15 = every 15 minutes)
,	List (e.g., MON,WED,FRI)

Examples of Cron Expressions in Salesforce

Task	Cron Expression	Meaning
Daily at 6 AM	0 0 6 * * ? *	6 AM every day
Every Monday at 9 PM	0 0 21 ? * MON *	9 PM every Monday
1st of every month at 1 AM	0 0 1 1 * ? *	1 AM on the first day of each month
Every 15 mins	0 0/15 * * * ? *	Every 15 minutes
Weekdays at 8 AM	0 0 8 ? * MON-FRI *	8 AM from Monday to Friday

When and Why to Use Scheduled Apex

There are certain scenarios where automation tools like Flow are limited:

• When you need complex Apex logic to run periodically.
• When you need asynchronous batch processing.
• When data needs to be cleaned, recalculated, or synced regularly.

Scheduled Apex fills this gap by allowing you to schedule an Apex class to run at a specific time, using a Cron Expression.

Anatomy of a Scheduled Apex Class

To use Scheduled Apex, follow these steps:

1. Create a class that implements the Schedulable interface.
2. Override the execute(SchedulableContext sc) method.
3. Schedule it using System.schedule() and a Cron Expression.

Step-by-Step Example: Auto-Archiving Inactive Cases Every Sunday at 3 AM

Let’s build a job that archives inactive Cases (cases closed more than 90 days ago) every Sunday at 3 AM.

Step 1: Create the Apex Class

public class ArchiveInactiveCasesJob implements Schedulable {
    public void execute(SchedulableContext sc) {
        // Fetch Cases that are closed for more than 90 days
        List casesToArchive = [
            SELECT Id, Status, ClosedDate 
            FROM Case 
            WHERE Status="Closed" 
              AND ClosedDate < LAST_N_DAYS:90
        ];
        
        for (Case c : casesToArchive) {
            c.Status="Archived";
        }

        if (!casesToArchive.isEmpty()) {
            update casesToArchive;
            System.debug(casesToArchive.size() + ' cases archived.');
        } else {
            System.debug('No cases to archive.');
        }
    }
}

Step 2: Schedule the Job with a Cron Expression

You can schedule the job via Anonymous Apex in the Developer Console:

String cronExp = '0 0 3 ? * SUN *'; // Every Sunday at 3 AM
String jobName="Archive Inactive Cases Job";

ArchiveInactiveCasesJob job = new ArchiveInactiveCasesJob();
System.schedule(jobName, cronExp, job);

Breakdown of Cron Expression 0 0 3 ? * SUN *

• 0 → 0 seconds
• 0 → 0 minutes
• 3 → 3 AM
• ? → No specific day of the month
• * → Every month
• SUN → Every Sunday
• * → Every year

Real-World Use Cases

Here are some real-world scenarios where Cron-based Scheduled Apex is used:

Use Case	Frequency	Cron Expression
Data archiving	Weekly	0 0 2 ? * SAT *
External system sync (API callouts)	Daily	0 30 1 * * ? *
Monthly usage report generation	Monthly	0 0 6 1 * ? *
Clean up temporary records	Hourly	0 0 0/1 * * ? *
Salesforce-to-ERP invoice sync	Weekdays	0 0 5 ? * MON-FRI *

Salesforce Limits for Scheduled Apex

Before you go wild with scheduled jobs, keep these limits in mind:

Limit	Value
Max scheduled Apex jobs per org	25
Max concurrent Apex jobs (Queueable/Batches)	5
Max number of classes implementing Schedulable	No limit, but be cautious
Max number of jobs per user via UI	100

To see all scheduled jobs:

• Go to Setup → Scheduled Jobs

• From here, you can abort, reschedule, or monitor jobs.

Best Practices for Using Scheduled Apex

Practice	Description
Avoid Hardcoded Values	Use Custom Metadata or Custom Labels for thresholds or logic
Monitor Jobs	Check Scheduled Jobs regularly for failures or overruns
Use Try-Catch	Catch exceptions and send error emails/log errors
Clean Up Old Jobs	Unschedule jobs that are no longer needed
Use Batch Apex	If processing more than 50k records, combine with Batch Apex
Limit Schedule Count	Use single job to do multiple tasks (strategy pattern)

FAQ – Cron Expressions in Scheduled Apex

Conclusion

Cron Expressions’ Scheduled Apex is a great tool for adding time-based automation to your Salesforce setup. For lengthy, CPU-intensive, or background processes that must run without disturbing users, it’s perfect. Knowing the Cron syntax, structuring your code correctly, and following best practices are the keys to getting the most out of it. Scheduled Apex remains the standard tool in every developer’s toolbox, even as Salesforce continues to advance in sophistication.