Cron Expression Generator

About this tool

A cron expression is five space-separated fields, minute, hour, day of month, month and day of week, that tell a scheduler when to run a job. This cron expression generator builds the expression from a schedule picker or reads one you paste, explains it in plain English and lists its next 5 run times. The run times are worked out in your browser, in your browser's time zone or in UTC.

How to use the cron expression generator

1. Pick a schedule type, such as every N minutes, daily or weekly, and fill in the numbers. Choose Custom to type any expression or macro, such as */15 9-17 * * 1-5 or @daily.
2. Check the description and the next 5 run times.
3. Copy the expression into your crontab (crontab -e), CI file or scheduler, followed by the command to run.

The five fields of a cron expression

The ranges are from the POSIX crontab specification. Names and 7 for Sunday are extensions documented in the crontab(5) manual for Vixie-derived cron, which this tool accepts.

Special characters: * , - /

• * means every value of the field.
• , makes a list: 0 8,12,18 * * * runs at 08:00, 12:00 and 18:00.
• - makes an inclusive range: 1-5 in the last field is Monday to Friday.
• / adds a step to * or a range: */2 in the hour field is every two hours, and 1-9/2 is the same as 1,3,5,7,9.

Lists and ranges are POSIX; steps are a Vixie cron extension.

Macros: @reboot, @daily and friends

Vixie-derived cron accepts a macro in place of all five fields. The crontab(5) manual defines them as extensions, not POSIX:

The day-of-month and day-of-week OR rule

When both day fields are restricted, POSIX says a day matches if either field matches. So 30 4 1,15 * 5 runs at 04:30 on the 1st, on the 15th and on every Friday, not only on Fridays that fall on the 1st or 15th. If either field is *, only the other one counts.

Vixie-derived cron adds a twist: the manual notes it only checks whether a field's first character is *. That makes 0 0 */2 * sun run on Sundays that are odd-numbered dates, where POSIX would run it on every Sunday and every odd date. This tool follows the Vixie rule. Some libraries, such as Python's croniter, use plain OR instead.

Crontab every 5 minutes

The expression is */5 * * * *, so a crontab line looks like */5 * * * * /path/to/script.sh. The step counts from the start of the range: minutes 0, 5, 10 … 55, not 5 minutes after you saved the file. A step only gives even gaps if it divides 60: */7 runs at minute 56 and then at minute 0, only 4 minutes later.

Common cron schedules

Each next-run column was computed with croniter, starting from Saturday, October 17, 2026 at 12:00.

Time zones and daylight saving time

A five-field expression has no time zone. The crontab(5) manual says the cron daemon runs in one configured time zone, and setting TZ inside a crontab changes only the environment of the commands, not when they run. Many servers run on UTC, so check before relying on a local hour.

Daylight saving time adds two gaps. Vixie-derived cron, as described in OpenBSD's cron(8) manual, treats changes of less than three hours specially for jobs at fixed times: jobs in a skipped interval run immediately, and jobs in a repeated interval are not run twice. Jobs that run more often than hourly are scheduled normally. The preview above simply leaves out times that do not exist in the chosen zone and lists a repeated clock time once, so switch to UTC to avoid the ambiguity. To convert run times to and from Unix time, use the Timestamp Converter.

Worked example

The generator opens on Every day, at a specific time with hour 9 and minute 0, so it shows 0 9 * * * and the description "At 09:00, every day." Reading the fields: minute 0, hour 9, any day of month, any month, any day of week. If your clock read Saturday, October 17, 2026 at 10:30, today's 09:00 has passed, so the next 5 run times would be:

1. Sun 2026-10-18 09:00
2. Mon 2026-10-19 09:00
3. Tue 2026-10-20 09:00
4. Wed 2026-10-21 09:00
5. Thu 2026-10-22 09:00

Not every scheduler uses five fields

• Quartz (Java) adds a leading seconds field and an optional year, and AWS EventBridge adds a year; both use ? in one of the day fields.
• GitHub Actions uses five-field POSIX syntax. Per the workflow syntax docs, schedules run in UTC by default, an optional timezone takes an IANA name such as America/New_York, and the shortest interval is once every 5 minutes.

Pasting a five-field expression into a six-field scheduler shifts every value one place, so the minute is read as seconds.

Common mistakes

• Writing * 9 * * * for "at 9". That runs every minute from 09:00 to 09:59; use 0 9 * * *.
• Restricting both day fields and expecting AND logic.
• Using 0 0 31 * * for month end. It skips months with fewer than 31 days.