Time/Numbers

Cron Parser

Parse a cron expression (5 or 6 fields, including @-shortcuts) — a plain-language schedule description and next run times in a chosen time zone.


                    

A cron expression is a compact five- or six-field schedule format (minute, hour, day of month, month, day of week, sometimes seconds) that's hard to read at a glance. This tool translates it into plain language and lists the next run times in your chosen timezone.

How to use it

Common uses

Things to keep in mind

In classic cron, the day-of-month and day-of-week fields combine with OR rather than AND when neither is "*" — a frequent cause of unexpected extra runs.

The server running cron may be set to a different timezone than the one you're assuming — always confirm which timezone the schedule is interpreted in.

Article about this tool: Cron expressions: how to decode a task schedule

Frequently asked questions

How does a 6-field cron expression differ from a 5-field one?

Standard cron uses 5 fields (minute, hour, day of month, month, day of week). Some schedulers add a sixth seconds field at the start of the expression — the tool recognizes both formats automatically.

What do shortcuts like @daily mean?

They're convenient aliases for common schedules: @daily corresponds to "0 0 * * *" (midnight every day), @hourly to "0 * * * *", and @weekly, @monthly, and @yearly work similarly.

In which timezone are the upcoming runs calculated?

In whichever one is selected in the "Timezone" field. The same cron expression gives a different absolute run time depending on the timezone, so make sure to specify the one your scheduler actually runs in.

Does daylight saving time affect when a job runs?

Yes, if the scheduled time falls on a nonexistent or repeated hour during the clock change. For critical jobs, it's more reliable to schedule outside the typical transition window or explicitly use UTC.

Why did an expression with both day-of-month and day-of-week fields specified run when I expected only one match?

In classic cron, these two fields are combined with OR rather than AND when neither is an asterisk — the job runs as soon as either condition matches, even if the other doesn't.

Articles: Time/Numbers

Unix time: why computers count time from 1970

Why January 1, 1970 became the reference point for time in most computer systems.

Number systems: why binary, octal, and hexadecimal exist

Why the color #FF5733 in CSS is written in hexadecimal digits instead of decimal.

Bitwise operations: how AND, OR, and XOR work at the bit level

How bitwise AND differs from logical AND, and why you'd operate on individual bits of a number at all.

Date difference: why counting days is trickier than it looks

Why naively subtracting dates can give the wrong result because of leap years.

Age calculation: why it's not just subtracting years

Why simply subtracting birth years can give an age one year higher than the real one.

Time zones: why UTC isn't the same thing as GMT

Why UTC never changes twice a year, while London time (GMT/BST) does.

Duration calculator: how to correctly add up hours, minutes, and seconds

Why adding minutes and seconds requires "carrying" the remainder to the next place, just like in decimal addition.

ISO 8601 duration: how to write a duration in a standard format

Why PT1H30M means "1 hour 30 minutes," not "1 minute 30 hours."

Week number: why different countries count weeks differently

Why January 1 sometimes falls into week 52 or 53 of the previous year under the ISO 8601 standard.

Roman numerals: how a system with no zero and no place value works

Why IV means 4, not 6, and how the subtraction rule works in Roman numerals.

IEEE 754: why 0.1 + 0.2 doesn't equal 0.3 in code

Why almost every programming language prints 0.1 + 0.2 as 0.30000000000000004.

Number to words: why turn digits into text

Why bank documents write an amount both in digits and in words at the same time.