What Day of the Week Is It?
See today's day name, its JavaScript and ISO 8601 index, weekday vs weekend status, and a full day-of-week reference table for use in code and cron expressions.
Day-of-week numbering in code
Almost every programming language and scheduling system uses a numeric index for days of the week — but they do not all agree on where to start. JavaScript (and standard Unix cron) start at Sunday = 0. ISO 8601 starts at Monday = 1, ending at Sunday = 7. Getting this wrong is a common source of off-by-one bugs in scheduled jobs.
In JavaScript, new Date().getDay() returns the JS/cron index (0–6). To convert to an ISO index, use d.getDay() || 7— Sunday's 0 maps to 7, all other days stay the same. In Python, date.isoweekday() returns ISO numbers directly; date.weekday() returns Monday = 0 (yet another variant).
Frequently asked questions
What day of the week is today?
The widget above shows today's day name in real time from your device's clock. Use the date picker to check any past or future date.
What number is each day of the week in JavaScript?
JavaScript's Date.getDay() returns 0 for Sunday, 1 for Monday, 2 for Tuesday, 3 for Wednesday, 4 for Thursday, 5 for Friday, and 6 for Saturday. This is the same numbering used by standard cron expressions.
What is the ISO 8601 day-of-week number?
ISO 8601 numbers days Monday=1 through Sunday=7. This differs from JavaScript which starts at Sunday=0. Most modern languages expose both: for example Python's datetime.isoweekday() returns ISO numbers while weekday() returns Monday=0.
How do I use day-of-week numbers in a cron expression?
Standard cron uses 0–6 for Sunday through Saturday (some implementations also accept 7 for Sunday). For example '0 9 * * 1' runs at 9 AM every Monday. '0 9 * * 1-5' runs weekdays. '0 0 * * 0' runs every Sunday at midnight.
Is Sunday a weekday or weekend?
In most Western countries Sunday is a weekend day, along with Saturday. The ISO 8601 standard defines Monday as the first day of the week, placing Saturday and Sunday at positions 6 and 7 as the weekend.