# The Week Number > Calculates the week number for any date using US or ISO methods. (iPhone/iPad app by Piet Jonas.) - Source: https://appshunter.io/ios/app/the-week-number/id315311121 (this page in markdown: same URL + `.md`) - Developer: [Piet Jonas](https://appshunter.io/developer/288060167) - Category: Reference, Utilities - Price: $0.99 - Rating: 1.00/5 from 1 App Store ratings · 4 written reviews indexed - Age rating: 4+ - Requires: iOS 15.6 · 1 MB - Languages: American English - Released: 2009-05-11 - Data updated: 2026-06-29 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/the-week-number/id315311121/reviews.md ## What is The Week Number? This application calculates the number of the week for any date in the past and the future. It can either use the US method (first day of week is a Sunday) or the ISO method (first day is a Monday, first week contains the first Thursday of the year). It updates the icon badge to the current week number on each start. ## Key features - Calculate week number for any date - Supports US week numbering (Sunday start) - Supports ISO week numbering (Monday start) - Icon badge displays current week number - Past and future date calculations ## Recent user reviews (4 of 4) All indexed reviews: https://appshunter.io/ios/app/the-week-number/id315311121/reviews.md ### 1/5 — Inefficient *2018-05-16* The week number displayed in the icon is static. It does not show the current week number. The current week number is only displayed when you open the app. There is also no close button on the app screen, so one must use the home button to minimize, and close the app by swiping. Features and function are inconvenient. Unless updates correct the icon display (fatal flaw in my opinion), I recommend against purchasing this app. ### 2/5 — Misleading *2011-07-24* The description says "calculates the number of the week for any date in the past or future." The sentence should say "calculate the number of the week for any YEAR!" I bought this thinking it could keep track of my newborns age/week. My son is 18 weeks now and it would be nice to have an App that would count the weeks staring on his B-day. Wasted my 99 cents. ### 1/5 — Does not update *2010-11-08* The thing has the number on the icon but it does not update. I.e. I click on it, enter today's date (should be automatically) and the week number goes to the correct number. Hit the home button, and wallaa, the icon still shows the old week number. Change between US and ISO, still no update of icon. I uninstalled the thing. ### 1/5 — Iso wrong *2010-01-12* The iso format is wrong, this app starts the new week on a Saturday and not a Sunday ## Frequently asked questions about The Week Number ### How does The Week Number calculate week numbers? The Week Number calculates week numbers using two distinct methods: the US method, where Sunday is the first day of the week, and the ISO method, which designates Monday as the first day and follows specific rules for the first week of the year. ### Can I see the current week number without opening The Week Number? Yes, The Week Number updates its icon badge to display the current week number each time the app is launched, providing quick access to this information. ### What devices does The Week Number support? The Week Number is available for iPhone, iPad, and iPod devices. ### What is the age rating for The Week Number? The Week Number has an age rating of 4+. ### How often is The Week Number updated? The latest version, 1.4.3, was last updated on May 29, 2025. The app was initially released on May 11, 2009. ### Does The Week Number have ads? No, The Week Number does not contain advertisements. ### What is the price of The Week Number? The Week Number is a paid application and costs $0.99. ### What is the user feedback on The Week Number? Based on the provided data, The Week Number has a rating of 1.0 stars from 1 rating. ## Version history (last 5 releases) ### 1.4.3 — 2025-05-29 - bug fixed ### 1.4.2 — 2022-03-24 - bug fixed ### 1.4.1 — 2019-02-14 - support for iPhone X+ ### 1.4.0 — 2015-11-24 - support for the iPad multitasking (split view..) - support for iPhone 6, 6+ and iPad Pro ### 1.3.1 — 2014-05-15 - fixed wrong badge number in app icon ## More apps by Piet Jonas - [Game Counter](https://appshunter.io/ios/app/game-counter/id288060164) - [Workout](https://appshunter.io/ios/app/workout/id288240647) - [Compass](https://appshunter.io/ios/app/compass/id288420566) - [Contact Find](https://appshunter.io/ios/app/contact-find/id290153951) - [Thesaurus App](https://appshunter.io/ios/app/thesaurus-app/id291362860) - [Baseball Games](https://appshunter.io/ios/app/baseball-games/id291533429) All apps by Piet Jonas: https://appshunter.io/developer/288060167 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-29.*