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Date Range Overlap Calculator

Find the inclusive overlap of two calendar date ranges.

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02
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Find the inclusive overlap of two calendar date ranges online

Find the inclusive overlap of two calendar date ranges. Use this for calendar planning or date-data preparation. The example uses a fixed date so the result can be checked independently of today’s date or your device timezone.

How to use it

Paste the date or duration in the demonstrated format. Review first range end, second range start, second range end. Choose Run tool and review the result. Copy or download the output when it matches your requirements.

Options and example settings

Option	Choices / value	Example default
First range end	Enter a value for first range end.	2026-10-20
Second range start	Enter a value for second range start.	2026-10-15
Second range end	Enter a value for second range end.	2026-10-30

Worked examples

Use this for calendar planning or date-data preparation. The example uses a fixed date so the result can be checked independently of today’s date or your device timezone.

Reproducible sample

Settings: First range end: 2026-10-20; Second range start: 2026-10-15; Second range end: 2026-10-30

Input:

2026-10-01

With the settings above, the output is:

Output:

{
  "start": "2026-10-15",
  "end": "2026-10-20",
  "overlapDays": 6
}

For this input, “overlapDays” is 6. These are the named fields in the example output.

Limitations and common mistakes

Gregorian calendar, UTC date boundaries. Use YYYY-MM-DD unless the tool explicitly requests another format; local daylight-saving rules are not inferred.
Inputs are limited to 250,000 characters in total. Invalid input is reported rather than silently corrected.

Frequently asked questions

How can I check the result?

Run the fixed worked example with the documented settings, compare its output, then check your own input format and units before copying a result.

Does this require an account?

No. This bundled tool runs in your browser without a conversion account.

How can I locate the inclusive overlap of two calendar date ranges online?

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.