Cron Expression

Next 5 Runs

Practical cron expression checks

Check server jobs, worker schedules, and alert timing as readable text plus upcoming run times before deploying them.

Validate schedules before release

Confirm that expressions such as */15 * * * * match the intended interval before they reach production jobs.

Share readable timing

Pair the raw expression with a human-readable explanation so teammates can review the schedule without memorizing cron syntax.

Runs in the browser

The expression is parsed locally in your browser and is not stored or sent to a separate server by this tool.

Errors you will hit

Is Sunday 0 or 7?

Standard cron accepts both, but some implementations reject 7. Using 0 is the safer choice.

Five fields or six?

Unix cron uses five fields: minute, hour, day, month, weekday. Spring and Quartz prepend a seconds field for six. A five-field expression pasted into Quartz shifts every value by one position.

The next run time looks wrong

When both day-of-month and day-of-week are set, most implementations run if either matches — an OR, not an AND. Check the server timezone and daylight saving as well.

Things to check

Day fields can differ

Schedulers can interpret day-of-month and day-of-week combinations differently, so verify critical jobs against the target runtime.

Seconds are runtime-specific

Some systems support a seconds field, while traditional crontab uses five fields. Match the format expected by your scheduler.

Day-of-month and day-of-week are OR

Setting both the third and fifth fields makes most implementations combine them with OR, not AND. The crontab guide explains this and how to work around it.

Step values are modulo, not intervals

*/15 matches minutes divisible by 15 rather than "every 15 minutes from now". So 7 */3 * * * fires at 00:07, 03:07, 06:07 and so on, not three hours from the current time.

The environment differs from your shell

Cron runs with a minimal environment, so a command that works in your terminal reports command not found. Use absolute paths or load the environment at the top of the script. Python virtualenvs and Node version managers are frequent offenders.

How to use it

Paste a 5-field cron expression and compare the explanation with the intended cadence.

Review the next five run times for start time, interval, month-end behavior, and weekend behavior.

Compare browser timezone with the timezone used by the actual server or scheduler.

Check spacing and field count before copying the expression into deployment config or documentation.

Real input and output

Weekday morning batch

Input

0 9 * * 1-5

Output

Runs at 09:00, Monday through Friday

Day-of-week starts at 0 for Sunday, so 1-5 means Monday to Friday.

Health check every 15 minutes

Input

*/15 * * * *

Output

Runs at minute 00, 15, 30, and 45 of every hour

Midnight on the first of the month

Input

0 0 1 * *

Output

Runs at 00:00 on day 1 of every month

Tools that pair well