Reference · Dates

date.days_between

date.days_between(str, str) -> int

What it does

The number of days from one date to another, the second minus the first: the nights of a stay, the age of an order in days. Negative when the second date is earlier. It takes dates, not date-times: for the time between two instants subtract their date.ms.

Examples

print(date.days_between("2026-11-05", "2026-11-14"))print(date.days_between("2026-11-14", "2026-11-05"))print(date.days_between("2024-01-01", "2025-01-01"), date.days_between("2023-01-01", "2024-01-01"))

9-9366 365

Edge cases

• The same date twice is 0.
• It counts calendar days, with no daylight saving to lose or gain an hour.
• The whole calendar fits in an int: from year 1 to year 9999 is about 3.65 million days.

print(date.days_between("2026-10-27", "2026-10-27"))print(date.days_between("2026-10-24", "2026-10-26"))print(date.days_between("0001-01-01", "9999-12-31"))

023652058

Errors

A date-time, text that is not a date, or any other value in either place is a runtime error, not an error value.

print(date.days_between("2026-10-27", "2026-10-27T00:00:00Z"))

line 1: `date.days_between` expects a date (YYYY-MM-DD) as argument 2, got the date-time "2026-10-27T00:00:00Z" (`date.date_in` gives its date)

Chaining

In a pipeline the first date comes first, so from | date.days_between(to):

print("2026-10-27" | date.days_between("2026-12-25"))let stays = [["2026-11-05", "2026-11-14"], ["2026-12-01", "2026-12-03"]]print(stays | map((s) => date.days_between(s[0], s[1])) | sum)

5911

See also

date.months_between, date.add_days, date.ms, date.date_in, date.weekday

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