About

Date intervals compound complexity when unsorted. Project timelines, booking systems, and scheduling conflicts demand precise chronological ordering. Manual sorting invites errors - a single misplaced range cascades into scheduling collisions or resource conflicts. This tool parses intervals in ISO-8601 (2024-01-15), European (15.01.2024), and US (01/15/2024) formats, computing duration as d = end − start in milliseconds, then converting to human-readable days and hours.

The sorting engine implements stable comparison: intervals with identical primary keys preserve input order. Overlap detection applies the intersection test where two intervals A and B overlap when A_start ≤ B_end ∧ B_start ≤ A_end. Gap analysis identifies unoccupied periods between consecutive sorted ranges. Results persist locally, surviving browser sessions. Assumes all dates share a common timezone context - cross-timezone intervals require manual UTC normalization before input.

Formulas

Interval duration is computed as the absolute difference between endpoint timestamps:

d = |t_end − t_start|

where t_end and t_start represent Unix timestamps in milliseconds. Conversion to days applies:

d_days = d86,400,000

Two intervals A = [a₁, a₂] and B = [b₁, b₂] overlap when both conditions hold:

a₁ ≤ b₂ ∧ b₁ ≤ a₂

Gap detection between consecutive sorted intervals identifies unoccupied spans:

gap = B_start − A_end where gap > 0

The comparator function for stable sorting uses lexicographic ordering on selected keys:

cmp(A, B) =

{

−1 if A_key < B_key1 if A_key > B_key0 otherwise

where key ∈ {start, end, duration, label}.

Reference Data

Input Format	Pattern	Example	Region
ISO-8601	YYYY-MM-DD	2024-03-15	International
ISO with Time	YYYY-MM-DDTHH:MM	2024-03-15T14:30	International
US Format	MM/DD/YYYY	03/15/2024	United States
European Format	DD.MM.YYYY	15.03.2024	Europe
UK Format	DD/MM/YYYY	15/03/2024	United Kingdom
Long Month	Month DD, YYYY	March 15, 2024	International
Short Month	DD Mon YYYY	15 Mar 2024	International
Compact	YYYYMMDD	20240315	Technical

Sort Criteria	Description	Use Case
Start Date (Asc)	Earliest start first	Project timelines, chronological review
Start Date (Desc)	Latest start first	Recent-first analysis
End Date (Asc)	Earliest end first	Deadline prioritization
End Date (Desc)	Latest end first	Long-term planning
Duration (Asc)	Shortest intervals first	Quick task identification
Duration (Desc)	Longest intervals first	Major project focus
Label (A-Z)	Alphabetical by name	Reference lookup

Duration Unit	Milliseconds	Conversion
Second	1,000	1 s
Minute	60,000	60 s
Hour	3,600,000	60 min
Day	86,400,000	24 h
Week	604,800,000	7 d
Month (avg)	2,629,746,000	30.44 d
Year (avg)	31,556,952,000	365.25 d

Frequently Asked Questions

Intervals that share an exact boundary point (where A ends precisely when B starts) are classified as adjacent, not overlapping. The overlap condition requires strict inequality: A's end must exceed B's start for overlap to occur. The tool displays adjacent pairs separately from true overlaps.

The parser defaults to US format (MM/DD/YYYY) for slash-separated dates unless you specify otherwise in settings. European format (DD.MM.YYYY) uses dot separators. For unambiguous results, use ISO-8601 format (YYYY-MM-DD) which eliminates month/day confusion entirely.

Duration computes raw millisecond differences between timestamps. DST transitions may cause 23-hour or 25-hour days. For critical scheduling across DST boundaries, input times explicitly (e.g., 2024-03-10T01:00 to 2024-03-10T03:00 spans 1 hour due to spring-forward, not 2 hours). The tool displays actual elapsed time, not calendar arithmetic.

Yes. Zero-duration intervals (same-day events) are valid and sort by their date position. Duration displays as 0 days, 0 hours. This supports milestone markers or single-point events within a timeline.

The sorting algorithm preserves original input order for intervals with equal keys. If three intervals all start on 2024-01-15, they appear in the sequence you entered them. This stable sort property ensures predictable, repeatable results.

Gap analysis only identifies unoccupied time between non-overlapping consecutive intervals. Overlapping intervals produce no gaps in their shared region. The tool first sorts by start date, then scans sequentially - a gap exists only when interval B starts after interval A ends.