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A days between dates calculator counts the exact number of calendar days separating two dates. It can also express the difference in weeks and months for longer time spans.

公式

days = end_date - start_date (accounting for leap years)

start: Start date (date) — Beginning date (YYYY-MM-DD)
end: End date (date) — Ending date (YYYY-MM-DD)
days: Days between (days) — Total calendar days elapsed

ステップバイステップガイド

1Convert both dates to milliseconds since epoch
2Subtract start from end date in milliseconds
3Divide by 86,400,000 (ms per day)
4Result is the absolute number of calendar days

解いた例

入力

Jan 1 to Dec 31 same year

結果

364 days (365 in a leap year)

入力

Mar 1 to Jun 30

結果

121 days

入力

Today to your birthday

結果

Exact days remaining

よくある質問

Does the calculation include both start and end dates?

Usually not. The result is the number of complete days between. For example, Mon–Tue = 1 day.

How do leap years affect the count?

Leap years (divisible by 4, except centuries not divisible by 400) add February 29. The calculator handles this automatically.

What about time zones?

Days are calendar days regardless of time zone. Time differences affect hours/minutes; date calculations count calendar days.

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