Cron Next Run Calculator
Calculate the next several run times for a given cron expression and timezone.
About Cron Next Run Calculator
A cron expression's 5 fields (minute, hour, day-of-month, month, day-of-week) each define a set of matching values, and a candidate minute must satisfy all fields — except for the classic cron quirk where, if both day-of-month and day-of-week are restricted (not '*'), a match on either field alone is sufficient (an OR rather than AND between just those two fields). This calculator walks forward minute-by-minute from the current time, checking each candidate against the parsed field sets, until it finds the requested number of upcoming matches — the same effective logic the cron daemon itself uses to decide when to fire.
Formula
Day-of-month / day-of-week matching rule
A candidate day matches if: (DOM='*' AND DOW='*') OR (DOM='*' AND dow_matches) OR (dow='*' AND dom_matches) OR (dom_matches OR dow_matches) when both are restricted
Worked example
With the default values below, Cron Next Run Calculator returns Next Run Time of 2026-10-29 08:00:00 UTC. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Cron Expression (min hour dom month dow)
- 0 */4 * * *
- Number of Next Occurrences to Showaccepts 1–20
- 5
- Start Fromone of Now (current server time)
- Now (current server time)
Results
- Next Run Time
- 2026-10-29 08:00:00 UTC
- Upcoming Run Times
- 2026-10-29 08:00:00 UTC 2026-10-29 12:00:00 UTC 2026-10-29 16:00:00 UTC 2026-10-29 20:00:00 UTC 2026-10-30 00:00:00 UTC
- Occurrences Found
- 5
Step by step
- 1Values used
- 2Day-of-month / day-of-week matching rule
- 3Next Run Time= 2026-10-29 08:00:00 UTC
- 4Upcoming Run Times= 2026-10-29 08:00:00 UTC 2026-10-29 12:00:00 UTC 2026-10-29 16:00:00 UTC 2026-10-29 20:00:00 UTC 2026-10-30 00:00:00 UTC
- 5Occurrences Found= 5
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why does '0 0 15 * 1' run on both the 15th of the month AND every Monday?
This is a well-known cron quirk: when both day-of-month and day-of-week are restricted to specific values (not '*'), cron treats them as an OR, not an AND. So this expression fires at midnight on the 15th of every month, and separately at midnight every Monday — not only on Mondays that happen to be the 15th.
What timezone does this calculator use for 'now'?
It calculates relative to the current server/browser time context in which this calculator runs. Real crontabs run in the timezone configured for the cron daemon (often UTC or system-local time, sometimes overridable per-job via a CRON_TZ variable in modern cron implementations) — always verify against the actual server's `date` and cron configuration for production scheduling decisions.
Does this support special cron strings like @daily or @reboot?
No — this calculator expects standard 5-field cron syntax (minute hour dom month dow). Special strings like @daily, @hourly or @reboot are shorthand supported by some cron implementations (like cron/vixie-cron) but would need to be translated to their 5-field equivalent first (e.g. @daily = '0 0 * * *') before using this calculator.