Date Calculator
How to Use
- Choose a mode: "Countdown", "Business Days", or "Week Number".
- Countdown: enter a target date to see the time remaining (or elapsed) in days, weeks, and months.
- Business Days: enter a start and end date, optionally add holiday dates (one per line) to exclude them from the count.
- Week Number: enter any date to see its ISO 8601 week number and year.
- Results update instantly as you type — no need to click Calculate.
Frequently Asked Questions
QHow is the countdown calculated?
The countdown takes the difference between the target date and right now, and shows it broken down into days, hours, weeks, and months. If the date is in the past, it shows how much time has elapsed instead.
QWhat counts as a business day?
By default, business days are Monday through Friday. Any dates you list in the holidays box (one per line, in YYYY-MM-DD format) are also excluded from the count, even if they fall on a weekday.
QWhat is an ISO week number?
The ISO 8601 standard divides the year into 52 or 53 numbered weeks, each starting on Monday. Week 1 is the week containing the year's first Thursday. This numbering is widely used in business, manufacturing, and government scheduling.
QCan week numbers go up to 53?
Yes — most years have 52 ISO weeks, but years where 1 January falls on a Thursday (or it's a leap year starting on Wednesday) have 53 weeks.
QIs my data sent to a server?
No. All date calculations happen locally in your browser using JavaScript. Nothing is sent to or stored on any server.
About This Calculator
Countdown and business day calculations use standard JavaScript Date arithmetic. Business days exclude Saturdays, Sundays, and any dates you list as holidays. Week numbers follow the ISO 8601 standard (weeks start on Monday; Week 1 contains the year's first Thursday).
