Cron Expression Validator
Validate a 5-field cron expression and see its schedule described in plain English.
How this tool works
Paste your cron expression
A standard 5-field schedule like "0 2 * * *".
Each field is checked individually
Out-of-range values are flagged with the specific field and valid range, not a generic syntax error.
Read the plain-English schedule
A valid expression is translated into a sentence like "Every day at 2:00 AM."
Ship with confidence
Confirm the schedule says what you meant before it goes into a crontab or deployment config.
Quick facts
- Category
- Validators
- Best for
- Double-checking a deployment's cron schedule before it ships
About this tool
Paste a standard 5-field cron expression (minute, hour, day of month, month, day of week) to check that each field uses a legal value, range, list, or step for its position - a "13" in the month field or a "70" in the minute field gets flagged with the specific field and reason, rather than a generic syntax error. Once the expression checks out, it’s translated into a plain-English sentence describing when it actually fires, so you can confirm "0 2 * * *" really does mean "every day at 2:00 AM" without mentally decoding five asterisk-and-number fields. This targets the common 5-field Unix cron syntax and doesn’t cover vendor-specific extensions like seconds fields, "@daily" shorthand, or "L"/"W" day modifiers.
Why use this tool
Plain-English translation
Turns five cryptic fields into a sentence you can actually read and confirm at a glance.
Field-specific error messages
Points to exactly which field is out of range, rather than a generic "invalid cron expression."
Standard 5-field focus
Targets the classic Unix cron syntax most schedulers actually use, without extra format guessing.
Catches misplaced values
An hour value typed into the minute field gets caught before it reaches production.
Frequently asked questions
The standard 5-field Unix cron format: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-6, where 0 is Sunday), separated by spaces. Each field accepts "*", a single number, a range like "1-5", a comma-separated list, or a step like "*/15".
The most common cause is a value out of range for its position - for example, putting an hour value like "14" in the minute field, or a day-of-week value above 6. The error message names the specific field and the valid range so you can spot which one is misplaced.
No - this validates the classic 5-field cron syntax used by cron itself and most schedulers. Shorthand macros like "@daily" and 6-field formats with a leading seconds value (used by some libraries) aren’t recognized and will be reported as having the wrong number of fields.
Explore more free tools
Formatters, converters, validators, and generators - all free and running entirely in your browser.
Browse more tools