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All content and tools from datums-rechner.com at a glance.
01. Calculators & Tools
02. Guide
Leap Years Explained: Why February 29th Exists
Everything you need to know about leap years. Learn why our calendar needs an extra day every four years and how it is calculated.
What is a Business Day? Definition & Rules
Learn everything about the term business day, how it differs from a working day and what to consider for deadlines.
How Many Weeks Are in a Year?
Does a year always have 52 weeks? Find out more about ISO weeks, leap years, and why some years have 53 weeks.
ISO 8601 Standard Explained: Date & Time
Why ISO 8601 is the most important standard for digital time measurement and how to apply it correctly.
03. Common Time Spans
04. Legal
ISO 8601 Certified
All calculations on this website are subject to strict mathematical controls and comply with the international standard for date and time specifications.