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Cron Expression Explainer
Type a standard 5-field cron expression to translate it into plain English and preview the next 5 run times in your local time. Everything runs locally in your browser — nothing is uploaded.
min 0-59hour 0-23day-of-month 1-31month 1-12day-of-week 0-7
Next 5 run times (your local time)
What is a cron expression?
A cron expression is a compact string that tells a job scheduler — such as Unix/Linux cron, a CI pipeline, or a cloud function trigger — exactly when to run a task. The standard format has five space-separated fields, read left to right:
| Field | Allowed values | Meaning |
|---|---|---|
| Minute | 0-59 | Minute of the hour |
| Hour | 0-23 | Hour of the day (24-hour clock) |
| Day of month | 1-31 | Day of the month |
| Month | 1-12 | Month of the year |
| Day of week | 0-7 | Weekday, where 0 and 7 are both Sunday |
For example, 0 9 * * 1 means "at 09:00, only on Monday", and */15 * * * * means "every 15 minutes".
How to use it
1. Type a 5-field expression into the box above, or click a preset to fill it in. 2. The explanation and the next five run times update automatically as you type — or click Explain. 3. Read the plain-English summary, then check the upcoming run times, which are shown in your browser's local time zone.
Supported cron syntax
This explainer handles every common operator: * matches any value, a single number matches one value, a-b is an inclusive range, a,b,c is a list, and a step like */n or a-b/n selects every n-th value across that range. You can freely combine them, for example 0,30 9-17 * * 1-5 for "on the hour and half-hour, between 9 AM and 5 PM, Monday to Friday".
How are the next run times calculated?
The tool starts from the next whole minute and walks forward one minute at a time, checking each candidate minute against all five fields until it has collected five matches. Following standard cron behaviour, when both the day-of-month and day-of-week fields are restricted (neither is *), a day matches if either condition is satisfied. The search is capped at roughly two years; if a schedule can never fire (for instance an impossible date like February 30th), the tool tells you instead of looping forever.
FAQ
Does this support the optional seconds field or the year field? No. This tool uses the classic 5-field crontab format (minute, hour, day-of-month, month, day-of-week). Quartz-style 6- and 7-field expressions are a different dialect.
What time zone are the results in? The next run times are computed in your device's local time zone, shown at the bottom of the list. Real cron daemons usually run in the server's time zone, so confirm where your job actually executes.
Are named values like JAN or MON supported? This explainer expects numeric fields, which work in every cron implementation. Use 1 for Monday through 5 for Friday, and 0 or 7 for Sunday.
Is my data uploaded anywhere? No. Parsing and all date math happen entirely in your browser with plain JavaScript. There is no backend and no network request.