Cron explained with real examples (and incident-causing mistakes)

5-field cron guide: how to read it, production examples, common mistakes, and timezone checklist.

Updated: 2026-03-22

On this guide

How to use this guide well

These guides are more useful when you read them as operational help, not as filler documentation.

Start from the section that matches the failure

Do not read linearly if you do not need to. Jump to the section that looks closest to the incident, payload, or config you are debugging.

Copy only after you understand the constraint

The useful part is usually in the caveat, not in the snippet itself: timezone, dialect, schema, audience, type inference, or portability.

Then validate with the tool

Once the reasoning is clear, use the related tool to inspect the real value, payload, or expression instead of working from memory.

A quick scan before you dive in.

Sections

Code examples

A short workflow tuned to the type of issue this guide covers.

Validate the exact dialect

Check whether the platform expects standard cron, Quartz, or a YAML subset before reusing examples blindly.

Inspect rendered values

Focus on indentation, booleans, numeric coercion, and timezone assumptions instead of only checking that the file “looks right”.

Test the production interpretation

Confirm the next run time, parsed config, or rendered manifest in the same environment where the job or deploy will execute.

Most incidents come from misunderstood expressions, not schedulers. Your goal is to read and explain when it runs.

minute hour day-of-month month day-of-week. This tool focuses on 5-field cron.

Copy and adjust:

text

*/5 * * * *
0 2 * * *
30 9 * * 1-5
0 0 1 * *

Wrong field ordering, out-of-range values, timezone assumptions, DOM vs DOW confusion.

Seconds field supported? No.

Why different results across platforms? Cron dialects differ.

Timezone? Document UTC vs local.

Use the matching tool when you want to validate or reproduce the issue described in this guide.

Convert YAML to JSON and JSON to YAML with clear validation.

Validate cron expressions and explain their meaning.

Move between deep guides and shorter task-focused articles so the site works like a connected knowledge base, not a dead end.

Real-world comparison: when to choose YAML or JSON, examples, pitfalls (indentation/types), and a production checklist.