Exclusive vs inclusive counting
By default this calculator counts exclusively: it counts the start date but not the end date, the same way a hotel counts nights. Check in on the 10th and out on the 13th and you pay for 3 nights, because the check-out day is not one of them. Tick "Include the end date" for inclusive counting, which adds one day and matches how people count event days: a festival from the 10th to the 13th runs for 4 days, since you are there on both endpoint dates. Neither convention is wrong; the right one depends on whether the final date is itself a full day of whatever you are counting.
The calendar breakdown in years, months and days is a different kind of answer from the raw day count, because months are not all the same length. The breakdown depends on which specific months your span crosses: a span that passes through February consumes a whole month in as few as 28 days, while one crossing July and August needs 62 days for its two months. That is why two spans with the identical number of total days can show different months-and-days figures.
Frequently asked questions
Should I count inclusive or exclusive?
It depends on whether both endpoints count as full days. A hotel stay from the 10th to the 13th is 3 nights, exclusive counting, because check-out day is not a night. A festival running from the 10th to the 13th is 4 days, inclusive counting, because you attend on both endpoint dates. Ask yourself whether the final date is itself one of the things being counted.
Why do two 90-day spans give different month breakdowns?
Months are not the same length, so the calendar breakdown depends on which months the span crosses. Ninety days starting 1 January passes through February, which is short, and comes out as roughly 3 months. Ninety days starting 1 July crosses only 31-day and 30-day months and falls just short of 3 months. Both spans contain exactly the same number of days.
Does daylight saving time affect the count?
No. This calculator does all of its arithmetic on UTC midnights, so every day counts as exactly 24 hours regardless of clock changes. A 23-hour or 25-hour day in your local time zone still counts as one calendar day, which is what you want when counting dates.