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.