📅 Date & Time Reference Library
Quick-reference tables for dates, times, and calendars — from federal holidays and week numbers to time zones. All free and no account required.
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Federal Holidays
US federal public holidays for 2025 and 2026 with observed dates.
📅Week Number Lookup
ISO week numbers for every week of the year with start and end dates.
🗓️Day of Year Reference
Day number for each date: ordinal day counts for regular and leap years.
📆Calendar Reference
Month lengths, quarter boundaries, and common calendar constants.
🌍Time Zone Reference
UTC offsets for major world time zones with DST notes.