Free Cron Expression calculator with clear step-by-step results.
Turns a cron interval into execution counts and the compute time they consume, and flags the failure mode that catches most schedules out: a job whose average duration exceeds its interval will start again before the previous run finishes unless it holds a lock.
Executions per day
Runs = active hours x 60 / interval minutes
Annual compute
Hours = runs per year x average duration seconds / 3600
Serverless and CI platforms bill per invocation and per second of runtime, so a five-minute cron is 105,000 invocations a year - a very different bill from an hourly one.
Take an advisory lock or use a scheduler with concurrency limits. Cron itself has no notion of a previous run still being in progress.