Zerdly

Cron Expression Parser

Parses a crontab expression and explains its schedule in plain English.

100% FreeRuns in your browserBasic
How to use this calculator

Expression

minute hour day-of-month month day-of-week — e.g. */15 9-17 * * MON-FRI

Blank = now.

Build an expression field by field
minute0–59
hour0–23
day of month1–31*
month1–12*
day of week0–6

Result: 0 9 * * 1-5 — At 09:00, on Monday, Tuesday, Wednesday, Thursday and Friday.

Ranges: minute 0–59, hour 0–23, day 1–31, month 1–12 or JAN–DEC, weekday 0–7 or SUN–SAT (0 and 7 are Sunday). @hourly, @daily, @weekly, @monthly and @yearly are accepted. Quartz syntax (L, W, #, ?) and a seconds field are not.

Schedule

At 09:00, on Monday.

minute
0
hour
9
day of month
every value (1–31)
month
every value (1–12)
day of week
1

Daylight saving: a time skipped when clocks go forward does not run here, and a time repeated when they go back runs once. Real schedulers differ — check yours. This page explains a schedule; it does not create a job.

Runs entirely in your browser. Your input is not uploaded or stored.

How the method works

One instant, many wall-clock readings
Illustrative method
One instant, many wall-clock readingsA vertical line marks the instant Unix time 0. It crosses three time-zone rows: UTC reads 1970-01-01 00:00:00, Australia/Perth reads 08:00 the same day and America/New_York reads 19:00 on 31 December 1969.epoch 0 sUTCUTC+00:001970-01-01 00:00:00Australia/PerthUTC+08:001970-01-01 08:00:00America/New_YorkUTC−05:001969-12-31 19:00:00Same instant → same epoch, different local text
Unix time 0 seconds (= 0 ms = 0 ns) is the instant 1970-01-01T00:00:00Z. Shown in Australia/Perth (UTC+08:00) it reads 1970-01-01 08:00; in America/New_York (UTC−05:00) it reads 1969-12-31 19:00. The time zone changes the wall-clock text, never the epoch number.

A cron schedule names wall-clock times in a zone; each run is one instant, and the same instant reads differently in another zone. Fixed example values for illustration — not your result.

How to use this calculator

  1. Enter a five-field cron expression (minute hour day-of-month month day-of-week), or a macro such as @daily — or build one field by field and apply it.
  2. Choose a time zone, a start time (blank = now) and how many runs to list.
  3. Read the plain-English schedule, each field's values, a timeline of the upcoming runs, and the next run times in your zone and UTC.

How it works

This is the Unix (Vixie) dialect: lists, ranges, steps, JAN–DEC and SUN–SAT names, and Sunday as 0 or 7. When both day-of-month and day-of-week are set, a day matches if EITHER does.

Next runs are found by walking calendar days in the chosen zone within a five-year horizon, so an impossible date such as 30 February returns nothing instead of hanging.

Daylight saving: a time skipped when clocks go forward does not run here, and a repeated time runs once. Real schedulers differ, and Quartz syntax (L, W, #, ?) and seconds fields are rejected.

Worked example

0 9 * * 1. At 09:00, on Monday. From 2026-10-10 UTC the next run is 2026-10-12 09:00. 0 0 1 * 1 runs on the 1st AND every Monday.

Common mistakes

  • Expecting day-of-month and day-of-week to combine with AND.
  • Pasting a six-field Quartz expression.
  • Forgetting the server's time zone when reading run times.

Tips

  • Runs entirely in your browser. Your input is not uploaded or stored.

Frequently asked questions

Which cron format?

Standard five-field Unix cron (no seconds field), plus the common @ macros except @reboot.

Privacy?

Runs entirely in your browser. Your input is not uploaded or stored.

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Cite this tool

Zerdly. (2026). Cron Expression Parser. Retrieved from https://www.zerdly.com/tools/cron-expression-parser/

Tip: Enter any known values to calculate the remaining results.

Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.