Cron Expression Explainer
Translate a cron expression into a plain-English description, a labeled field breakdown, and a short preview of upcoming run times. Supports 5/6/7-field expressions and common nicknames like @daily.
Input
5 fields, 6 fields (leading seconds or trailing year), 7 fields (seconds + year), or a nickname like @daily.
Only affects the next-run preview below. Leave blank to use the current time (UTC).
Output
| Field | Value |
|---|---|
| No data yet | |
| # | Date & Time | Day |
|---|---|---|
| No data yet | ||
Guides
What this tool does
Paste a cron expression and get back three things at once: a plain-English description of when it runs, a labeled breakdown of each field, and a short preview of the next few times it actually fires.
Cron syntax is compact but easy to misread — is 1 * * * * "the 1st minute of every hour" or "1 AM every day"? This tool removes the guesswork instead of asking you to mentally re-derive it.
How to use it
- Enter a cron expression, e.g.
0 9 * * 1-5(9:00 AM on weekdays), or a nickname like@daily. - Read the plain-English description and the field-by-field breakdown.
- Optionally set a Reference Time to preview run times from a specific moment — leave it blank to use the current time (UTC).
Supported formats
- 5-field standard: minute, hour, day-of-month, month, day-of-week.
- 6-field: either a leading seconds field, or a trailing year — this tool detects which from the expression itself, the same way it's detected in the description.
- 7-field: seconds, then the standard five, then a trailing year.
- Nicknames:
@yearly/@annually,@monthly,@weekly,@daily,@hourly.
All accept *, comma lists (1,15,30), ranges (9-17), and step values (*/15).
FAQ
Why doesn't the next-run preview show up for some expressions?
The next-run calculation can't handle a year field (only the description can) — a 7-field expression, or the year variant of 6-field, shows a note there instead of run times. Drop the year field if you need the run list too.
What time zone are the run times in?
UTC, always — there's no time zone conversion. If you leave Reference Time blank, it uses your browser's local time to seed the search, but the results themselves are UTC.
I need more than 5 upcoming run times, or a CSV download.
Use the Cron Next Run Calculator — it lists up to 10 run times for a standard 5-field expression with a downloadable CSV.
I need to build a cron expression from scratch, not explain one.
Use the Cron Expression Generator — pick your schedule from a form and it writes the expression for you.
Privacy
This tool runs entirely in your browser. Your cron expression and reference time are never uploaded to a server.
More ways to use this tool
REST API
curl -X POST https://api.iotools.cloud/v1/tool/cron-expression-explainer \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"cronExpression": "0 9 * * 1-5",
"referenceTime": "2024-01-01T08:00"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `cron-expression-explainer` tool (Cron Expression Explainer) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
Embed widget
<iframe
src="https://iotools.cloud/embed/cron-expression-explainer/"
width="100%" height="520" frameborder="0" scrolling="no" loading="lazy"
title="Cron Expression Explainer — iotools.cloud"
sandbox="allow-scripts allow-forms allow-same-origin allow-downloads allow-popups allow-popups-to-escape-sandbox"
allow="clipboard-write"
style="width:100%;border:1px solid #e5e7eb;border-radius:12px;overflow:hidden"></iframe>
<script src="https://iotools.cloud/embed.js" async></script>Drop this into your own page — free, no key required, just a link back.
| Cost per call | From 5 credits |
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