Cron Expression Checker
Cron Checker explains a Unix, Quartz, Spring or AWS cron expression in plain English and lists its next 10 run times, entirely in your browser.
30 * * * *Every hour, at 30 minutes past the hour
Read as Unix cron (auto-detected): minute hour day-of-month month day-of-week.
| Field | Value | Means |
|---|---|---|
| Minute | 30 | 30 |
| Hour | * | every hour |
| Day of month | * | every day |
| Month | * | every month |
| Day of week | * | every day of the week |
Next 10 runs
Calculating in your browser...
- 1
- 2
- 3
At a glance
- Accepts
- A cron expression
- Outputs
- The next 10 run times in your local timezone
- Where it runs
- Entirely in your browser, on your device
- What leaves your device
- Nothing - what you type stays in this tab
- Limits
- Shows the next 10 runs; uses your browser's timezone
- Account
- Not required - there is no sign-up
- Price
- Free, with no watermark and no usage cap
- Made by
- Visrut
- Last updated
- 8 October 2026
What does 0 0 * * * ? mean?
0 0 * * * ? means every hour, on the hour. It's Quartz syntax (Spring accepts it too) with seconds first: second 0, minute 0, every hour, every day of the month, every month, and ? for "no specific day of week". 0 * * * * ? is every minute at second 0, and 0 0 * * * ? * adds Quartz's optional year field (every year), so it's still hourly. In a Linux crontab, GitHub Actions or Kubernetes, which have no seconds field, the hourly schedule is 0 * * * *. More on that on the 0 0 * * * ? page.
Four cron dialects, one checker
The same characters mean different things depending on where the expression runs, so the checker shows which dialect it assumed and lets you switch:
- Unix cron (crontab, GitHub Actions, Kubernetes): 5 fields, minute first. Day of week 0-7, where 0 and 7 are Sunday. When both day fields are set, a day matching either one runs.
- Quartz: seconds first, 6 or 7 fields (the 7th is the year). Day of week 1-7 with 1 = Sunday. One of the two day fields must be
?. SupportsL,Wand#. - Spring: seconds first, exactly 6 fields. Day of week like Unix (1 = Monday). Both day fields must match when both are set.
- AWS EventBridge: 6 fields, minute first and year last, day of week numbered like Quartz.
A 6-field expression with ? is read as Quartz first. If it uses day-of-week numbers and is really for Spring, click Spring: 2 is Monday in Quartz but Tuesday in Spring.
How to use it
- Paste an expression, or click an example.
- Click Calculate. You get a plain-English description, a field-by-field table, warnings about this exact expression, and the next 10 runs.
- Check the dialect line under the description and switch it if the guess is wrong.
- Flip between your timezone and UTC to see when a server or CI runner will actually fire it.
Want a syntax refresher? See the cron cheat sheet.
Common schedules
Each page has the expression in Unix, Quartz/Spring and AWS form, the next runs, and the pitfalls specific to that schedule.
Seconds and minutes
Days and weeks
Months, quarters and years
Quartz expressions explained
Frequently asked questions
What is the frequency of the cron expression 0 0 * * * ?
Every hour, on the hour (minute 0, second 0), 24 times a day. It's Quartz or Spring syntax: the first field is seconds, and the ? in the last field means no specific day of week. The Unix cron version is 0 * * * *.
What is the frequency of 0 * * * * ?
Every minute, at second 0. In Quartz and Spring the leading 0 is the seconds field. Be careful not to write * * * * * ?, which runs every second.
What does 0 0 * * * ? * mean?
The same as 0 0 * * * ?: every hour on the hour. The seventh field is Quartz's optional year, and * means every year.
How does the checker know which cron format I typed?
By the number of fields and the syntax. Five fields is Unix cron, seven is Quartz (the only one with a year after seconds), and cron(...) is AWS EventBridge. Six fields could be Quartz, Spring or AWS, so it picks the first that parses, in that order, and offers the others as a switch.
Why do Quartz and Unix cron disagree about day-of-week numbers?
Unix cron and Spring count 0 (or 7) as Sunday and 1 as Monday. Quartz and AWS EventBridge count 1 as Sunday and 2 as Monday. Using day names such as MON-FRI avoids the difference.
Is my cron expression sent to a server?
No. Parsing, the description and the run times are all calculated in your browser. Nothing you type is sent anywhere.
What timezone are the run times shown in?
Your browser's timezone by default, with a UTC toggle. GitHub Actions uses UTC unless you set a timezone, so the UTC view is the one to check for workflows.