BYTETOOLS

Date Range Overlap Calculator

Compare two or more date ranges to find the shared interval, every pairwise overlap, the merged coverage and the gaps, with an inclusive end-date toggle.

9 days
Common to every range
29
Days covered in total

Shared interval

Every range covers Jan 12, 2026 – Jan 20, 2026 — 9 days.

Pairwise overlaps

PairOverlapDays
Range A × Range BJan 12, 2026 – Jan 20, 20269

Merged coverage

  • Jan 5, 2026 – Feb 2, 202629d

Gaps between ranges

No gaps — the ranges join up into one continuous block.

What is the Date Range Overlap Calculator?

The ByteTools Date Range Overlap Calculator takes two or more named date ranges and works out where they meet.

  • As many named ranges as you need, with two as the minimum
  • Interval common to every range, plus a table of every pairwise overlap
  • Merged coverage that coalesces ranges which overlap or simply touch
  • Gap list showing the stretches no range covers
  • Inclusive or exclusive end dates, applied consistently to every count
  • Copyable text report of the whole comparison

How to use the Date Range Overlap Calculator

  1. 1

    Name the first two ranges and give each one a start and end date.

  2. 2

    Press Add range for every extra range you want to bring into the comparison.

  3. 3

    Set whether the end date is included, matching how your own dates are written.

  4. 4

    Read the shared interval, the pairwise table, the merged coverage and the gap list.

  5. 5

    Copy the full report as text.

About the Date Range Overlap Calculator

The ByteTools Date Range Overlap Calculator takes two or more named date ranges and works out where they meet. It reports the interval common to every range, found from the latest start against the earliest end, and a pairwise table showing which individual pairs overlap and by how many days when no single interval is shared by all of them.

It also merges the ranges into their combined coverage and lists the gaps between them, so you can see both the total time covered and the days nothing covers at all. That is the shape of question behind holiday clashes, insurance cover, contractor availability, booking conflicts and project phases meant to run back to back.

One toggle decides whether the end date is part of the range, because leave systems and contracts disagree about that and it changes every count by a day. Add as many ranges as you need; everything is computed 100% locally in your browser and no dates are ever uploaded.

Frequently asked questions

How do you calculate the overlap between two date ranges?

Take the later of the two start dates and the earlier of the two end dates. If that start is not after that end, the pair overlaps and those two dates are the shared interval. This tool applies the same rule across every range at once, and separately to each pair.

Should the end date be included in a date range?

It depends on your source. Leave requests and contracts usually mean an inclusive end date, so 1 to 5 April is five days, while many software APIs use an exclusive end, making it four. The checkbox switches convention and every count updates with it.

What does merged coverage mean?

It is the ranges combined into as few continuous blocks as possible, by sorting them on start date and joining any that overlap or touch. It gives the total time covered by at least one range, which is not the same as adding the individual lengths when they overlap.

Can I compare more than two date ranges?

Yes. Press Add range as many times as you need. The shared interval is computed across all of them, and the pairwise table grows to cover every combination, so you can see precisely which pair is causing a clash rather than only that one exists.

Why is there no interval common to all my ranges?

Because at least one range ends before another begins, so no single day sits inside every one of them. The pairwise table still shows which pairs do overlap, and the gap list shows exactly where the coverage breaks down.

Related tools