Time & calendar

Calendar and scheduling math in one hub: add or subtract days, weeks, and months; count business weekdays between dates; convert weekly hours to full-time equivalent (FTE); look up ISO 8601 week numbers; and convert Unix epoch timestamps to readable dates. Cross-links to age, date difference, and time zone tools for everyday planning.

Date arithmetic hides more edge cases than most people expect. Adding a month to 31 January has no single correct answer, so tools clamp to the last valid day and results can differ between systems. Business-day counts here exclude weekends but not public holidays, which vary by country and sometimes by region, so add those yourself for contractual deadlines. ISO week numbering is its own convention: weeks start on Monday, week one is the week containing the first Thursday of the year, and early January can therefore fall in week 52 or 53 of the previous year — which is why an ISO week number sometimes disagrees with a wall calendar. Time-zone conversions use fixed UTC offsets and do not track daylight saving transitions, so verify any booking that lands near a changeover date.