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Dates & times

Natural dates, countdowns, durations, and clock math.

Write dates the way you say them: 10 june, next friday, today, 3 days ago. Spanish works too: hoy, mañana, próximo viernes. Add or subtract durations to move through the calendar.

10 june + 3 weeks
deadline = today + 45 days
deadline + 2 weeks
Wed, Jul 1, 2026
Sun, Oct 18, 2026
Sun, Nov 1, 2026

The gap between two dates

Subtract dates, or write "A to B", and you get a calendar-aware duration. Ask for a specific unit with "in days" or "in weeks" and the answer uses real calendar days, not 30-day months.

mar 3 to may 30
mar 3 to may 30 in days
2 months 27 days
88 days

Countdowns

"days until" counts whole days from today. "days since" looks backwards, and a date without a year means the most recent one that already happened.

days until dec 25
days since july 4
113 days
61 days

Clock math and durations

Times work like you would hope, and multi-part durations like 14 hours 30 min are understood as one thing. A duration stored in a variable works in both worlds: date math and unit conversions. To pin a time to a city and convert it across the world, see Timezones.

9:45am + 3h 15min
flight = 14 hours 30 min
flight to minutes
1:00 PM
14 hours 30 min
870 minutes

Workdays

workdays means Monday to Friday. Add them to hop over weekends, measure a range in them, or ask workdays until a date. Public holidays are not subtracted (that needs to know your country; coming later). weekday on tells you the day of the week for any date.

today + 10 workdays
10 March to 17 March in workdays
workdays until dec 24
weekday on March 9, 2024
Thu, Sep 17, 2026
5 workdays
80 workdays
Saturday

Timestamps and ISO dates

Convert any date to the formats machines use, and back. as timespan breaks a time quantity into readable parts.

today as iso8601
today as timestamp
1234567890 as date
72 days as timespan
2026-09-03T10:46:26+00:00
1788432386
Fri, Feb 13, 2009
10 weeks 2 days

What does not become a date

OtterCalc is careful with ambiguity. 5/2 is division, 2020 is a number, and a heading like "March budget" stays text. Dates only take over when the line clearly reads as one.

5/2
salary = 2020
March budget
2.5
2,020