How to use the cron expression parser
- Type a five-field cron expression, for example 0 9 * * MON-FRI, or click a preset.
- Read the English description and check the five field cards, which show what each part allows.
- Review the next five run times, shown in your time zone with a relative countdown, to confirm the schedule does what you expect.
- Fix any highlighted field using the error message, then copy the description or run times into your ticket or documentation.
Features
- Standard 5-field crontab syntax with * , - / and names like JAN or FRI
- @hourly, @daily, @midnight, @weekly, @monthly and @yearly shortcuts
- Human-readable description, for example 'At 09:00, on Monday through Friday'
- Next 5 run times computed in your local time zone, skipping daylight-saving gaps like real cron
- Errors that name the field and the valid range, plus detection of Quartz-only syntax
- Implements cron's day-of-month / day-of-week OR rule correctly
Reading the five fields
From left to right: minute (0–59), hour (0–23), day of month (1–31), month (1–12 or JAN–DEC) and day of week (0–7 or SUN–SAT, where both 0 and 7 mean Sunday). * means every value, 1,15 is a list, 9-17 is a range and */15 means every 15th value starting from the minimum. Combine them freely: 0 9-17/2 * * 1-5 runs at 9, 11, 13, 15 and 17 on weekdays.
The day-of-month and day-of-week rule
When both day fields are restricted, such as 0 0 1 * MON, classic Vixie cron runs the job when either matches: on the 1st and on every Monday. If one of the fields starts with * (for example */2), both must match instead. This catches many people out, so the tool states which rule applies and the next-run list reflects it.
Time zones and daylight saving
Cron daemons use the server's time zone, which on cloud machines is usually UTC. This page computes run times in your browser's time zone, so a job scheduled at 0 9 on a UTC server will not fire at 9 am local time unless you live in UTC. When clocks spring forward, times that don't exist locally (such as 02:30 on that night) are skipped, matching cron's behaviour.
Six fields, L, W and #
Quartz (Java), Spring and some cloud schedulers use six or seven fields with seconds and support L (last), W (nearest weekday) and # (nth weekday). Those are not part of the standard crontab format and are flagged as errors here. AWS EventBridge and Kubernetes CronJobs use the standard five fields.