WhichWeek

WhichWeek is the fastest way to know your ISO week number. Open the app and your current ISO week number is front and center — bold, clear, and impossible to miss. No digging through a calendar. No mental arithmetic. Just the week number. WEEK VIEW • Your current ISO week number, large and legible • The exact date range for that week (Monday to Sunday) • Step forward or back through weeks and years with the stepper controls • Tap Today to jump straight back to the current week • Leap year indicator so you never lose track of the extra day DAYS VIEW • Pick any two dates and instantly see the number of days between them • Broken down into full weeks and remaining days • Perfect for project planning, countdowns, and date arithmetic DESIGNED WITH CARE • Pure SwiftUI — fast, native, and responsive • Supports Dynamic Type for accessibility • Full Dark Mode and Light Mode support • Works in portrait and landscape • Available on iPhone, iPad, Mac, and Apple Watch ISO WEEK NUMBERS ISO 8601 defines week numbering used widely in business, finance, logistics, and project management across Europe and beyond. Week 1 is the week containing the first Thursday of the year. WhichWeek follows this standard precisely. NO ADS. NO TRACKING. NO SUBSCRIPTIONS. WhichWeek is a one-time purchase. No accounts required, no data collected, no network requests made.