Dates and durations · Gaps and business days
Count the days between two dates
From January 1 to January 3, the exclusive gap is 2, the inclusive count is 3. Both are right; they do not answer the same sentence. This tool shows both, without choosing for you.
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How the calculator works
The civil date difference is computed first (how many times the date advances). That is the exclusive gap: the 1st and the 3rd, the date advanced twice. The inclusive count adds 1 in absolute value (both bounds are “occupied” days). If the end precedes the start, both numbers are negative, with the same logic. No decomposition into months: for 2 years 5 months, the other calculator.
Formula and method
exclusif = datefin − datedébut
Number of calendar steps, signed.
inclusif = exclusif + 1 si exclusif ≥ 0, sinon exclusif − 1
Both dates of the pair are counted.
The debate “do we count the departure day?” has no universal answer. A 15-day appeal deadline is not a rental week “from the 1st to the 8th” (often 7 nights). By showing both, the page avoids imposing a convention. Business days (without Saturday–Sunday) are a third count, elsewhere.
Worked example
From July 1 to July 15, 2026
Start = 2026-07-01, end = 2026-07-15.
- Exclusive gap: 15 − 1 = 14 days (the date advanced 14 times).
- Inclusive count: 14 + 1 = 15 days (1st, 2, …, 15).
14 days (exclusive), 15 days (inclusive).
From January 1 to January 3, 2026
Start = 2026-01-01, end = 2026-01-03.
- Exclusive: 2.
- Inclusive: 3.
2 (exclusive) and 3 (inclusive).
Input notes
- Start date
- First day of the count (rental arrival, opening of a deadline, event start).
- End date
- Arrival day. Same YYYY-MM-DD format. Both dates must be valid (no Feb 31).
Assumptions and limits
Assumptions
- A “day” is a civil date, not 24 clock hours.
- Inclusive = both bounds. Exclusive = date difference.
- Reversed order: negative signs, same formulas.
Limits
- No noon cutoff (hotel “night”).
- No holidays or weekends: see business days.
- No years/months/days decomposition.
How to read the result
Rental July 1–15: many listings want 14 nights (exclusive); a parking “15 calendar days” often wants inclusive. Read the contract, then pick the line. For an age, 14 days do not say “0 months 14 days” the same way as a Jan 31: the decomposition remains the other page.
Common mistakes
Always adding 1 out of habit.
Only if both dates should count. An age gap in days is the exclusive (birth → today).
Forgetting that from the 1st to the 1st, exclusive is 0 and inclusive is 1.
Same day: zero calendar steps, one “occupied” day if you count the bound.
Using this for business days.
Saturday and Sunday are calendar days. The business-days tool removes them, with an optional holiday list.
Comparison
| Convention | Result | Example use |
|---|---|---|
| Exclusive | 14 | Nights, “how many days later” |
| Inclusive | 15 | Days present, “n calendar days” package |
| Weekdays (no holidays) | 11 | Mondays–Fridays in the inclusive interval |
Related calculations
- Date differenceThe main result is a decomposition: 2 years, 5 months, and 10 days, for example. Total days sit beside it. That is not the same need as “how many stay nights.”
- Business daysA business day here is Monday through Friday. Saturday is not a business day. Metropolitan France statutory holidays are optional. The interval is inclusive: start and end count. This is not a US federal-holiday calendar.
- Age calculatorThe age shown is civil: completed years, then months, then leftover days. It is not the number of days divided by 365.25. An empty “Age on” field means today.
Frequently asked questions
Which is the “right” way to count?
The one in the text you are applying. The tool gives both numbers, not a legal rule.
A statute, a house rule, or a rental site each set their convention. Counting both bounds or only the gap is not an algorithm debate. If the text says “the deadline runs from the following day,” that is not even simple inclusive: reread the clause, then type the dates it names.
Why not merge with the years/months/days gap?
Because search intent is not the same, and neither are the figures.
“How many days between the 1st and the 15th” expects 14 or 15. “How many years, months, and days since 2024” expects a decomposition. Merging both on one page drowns the result. The calculators link; they do not mix.
Are leap years handled?
Yes: Feb 29, if it is a valid date, counts like any other civil day.
Feb 28, 2024 to Mar 1, 2024, exclusive is 2 (the 29th exists). In 2025, Feb 28 to Mar 1, exclusive is 1. No special rule other than date validity.
How do I count a one-day event?
Same date in both fields: exclusive 0, inclusive 1.
That is the consistency test. If you need 1 for “the day of July 4,” take inclusive. If you measure a deadline that has not started, exclusive 0 is the right one.
Author and update
Written by Rédaction HexaCalc (editorial team). Content last updated: August 25, 2026. No third-party medical or financial review is claimed.
This calculation uses a standard mathematical identity. See also the methodology.
Remove weekends and holidays
The calendar count includes Saturdays and Sundays. Metropolitan France weekdays are computed separately, inclusive interval.
Calculate business daysCategory: Dates and durations