Cron Expression Tester

What is a Cron Expression Tester?

A Cron Expression Tester checks a five-field cron expression such as 0 9 * * MON-FRI and explains what each field matches in plain language. It then scans forward minute by minute from now to find the next five exact run times, which you can copy as ISO-style or localized timestamps.

How do the five fields work?

• Minute (0–59): picks the minute of each hour; */5 matches every 5 minutes.
• Hour (0–23): selects which hours run; 9-17 means 09:00 through 17:00.
• Day of month (1–31): selects days such as 1,15,31 or a range like 1-15.
• Month (1–12 or JAN–DEC): restricts the expression to certain months; names like JAN-DEC are accepted.
• Day of week (0–7 or SUN–SAT): 0 and 7 both mean Sunday; MON-FRI matches weekdays.

FAQ

• What syntax does the tool accept? Standard five-field cron syntax: *, */n, a-b, a-b/n and comma-separated lists like 0,15,30,45.
• Are month and weekday names case-sensitive? No — MON, mon and Mon are all accepted and can be mixed freely with numbers.
• Do day-of-month and day-of-week combine? Yes, like classic cron: when both are restricted, a date matches when either field matches.

Reading a cron expression

• The five fields are minute, hour, day-of-month, month and day-of-week.
• * means 'every' — * * * * * runs every minute.
• Lists, ranges and steps: 0,15,30,45; 9-17; */30.
• A known gotcha: a strict day-of-month and day-of-week can conflict, depending on the engine.

The timezone gotcha

Cron interprets time in the server's time zone, not yours. A job tuned against your calendar can fire hours off from what you expected after a server moves regions or daylight saving changes — the tester shows the resulting instants so the mismatch is obvious.