Counts the interval between two dates in days, weeks, months and years, and separately in working days. Dates entered the wrong way round are swapped rather than rejected.
Days are counted by subtracting the two dates at midday UTC, which keeps the arithmetic clear of daylight-saving shifts that would otherwise make some intervals an hour short and round to the wrong day. Months and years are counted by calendar boundaries rather than by dividing days, because months are not a fixed length. The working-day figure counts weekdays only: Saturdays and Sundays are excluded, and public holidays are not, since they vary by country and region and the tool has no way of knowing which apply to you.
Counting days precisely
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Inclusive counting changes the answer by one:
from Monday to Friday is four days between, or five days inclusive. Contracts and notice periods usually specify which they mean, and the checkbox lets you match it.
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Public holidays are not deducted:
the working-day figure excludes weekends only. Add your own holiday count for a country-accurate figure.
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Months are calendar units, not fixed lengths:
the month figure walks real calendar boundaries, which is why it will not equal the day count divided by thirty.
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Midday UTC avoids a real bug:
comparing dates at midnight across a daylight-saving boundary can leave an interval an hour short and round down a whole day.
Why the count happens at midday UTC
The [msm_tool slug="date-difference-calculator"] subtracts the two dates at midday UTC rather than at midnight, which keeps the arithmetic clear of daylight-saving shifts that would otherwise leave some intervals an hour short and round the result down to the wrong day entirely. It is a deliberate choice made specifically to avoid a real, well-documented bug rather than an arbitrary implementation detail.
Inclusive counting changes the answer by exactly one
Monday to Friday is four days between the two dates, or five days counted inclusively — both are legitimate readings of the same pair of dates, and contracts and notice periods usually specify which one they mean. The inclusive option exists specifically to match whichever convention actually applies to the situation at hand.
Working days exclude weekends only, and that is deliberate
The working-day figure removes Saturdays and Sundays but leaves public holidays untouched, since holidays vary by country, region and sometimes industry, and there is no reliable way to apply the right set without knowing exactly which jurisdiction is meant. Subtracting a known holiday count from the figure shown is the way to reach a genuinely country-accurate result.
Months are calendar units, not a fixed number of days
The month figure walks real calendar boundaries rather than dividing the day count by an average month length, which is exactly why it will not equal the total days divided by thirty — the same span of days can report as a different number of months depending on where in the year it actually falls.
Dates entered the wrong way round are handled, not rejected
Two dates given in reverse order are swapped automatically and the interval is reported as a positive figure, with nothing to correct and no error shown. Leap years are handled the same deliberate way: actual calendar dates are stepped through one by one, so a 29 February is counted exactly once whenever it genuinely falls inside the interval.