Date Range Overlap Calculator

How to use this calculator

Add one to thirty named date ranges. Choose whether their ending dates count. Calculate to see dates covered by at least two entries, the overlap common to every entry, unique covered days and gaps inside the overall date span.

Including both endpoints makes a same-date range one day. Excluding the end makes it empty. Unique coverage counts a date once regardless of how many entries contain it. Overlap across all entries is different from overlap across any two. Duplicate entries remain separate for overlap analysis but do not inflate unique coverage. Ranges may span up to 3,660 days overall.

A worked example

November 2–6 and November 5–10, 2026 share two dates when both endpoints count. Their union covers nine days. If ends are excluded, only November 5 is shared, and the union covers eight days.

Can I use this for hotel nights or cross-time-zone meetings?

This tool compares whole date labels. For checkout-exclusive nights and accommodation gaps, use Trip Nights. For times of day across different zones, use the Time Zones tools. This calculator does not turn a date range into elapsed hours.

Further reading: Inclusive and exclusive range semantics. Your entered rules determine this result.

Which calendar and years are supported?

Use Gregorian dates from 1900 through 2100. All ranges must fit within a 3,660-day window. End-date inclusion is explicit and applies to every range. Gaps are measured only inside the earliest starting date through the latest ending boundary; no outside coverage window is inferred.

What happens to my dates?

Calculations run on your device. Saving a calculation is optional and keeps it in this browser. A setup link contains the dates and settings you entered; anyone with the link can read them. Use one tab per saved calculator. Clear saved data from Privacy & settings.