Speedy Calculator

Date to Date Calculator

Everyday Life Updated October 25, 2026

Quick answer

The date to date calculator measures the time from one date and time to another in years, months and days, and in total weeks, days, hours, minutes and seconds.

Years
—
and months
—
and days
—
Total days
—
Total weeks
—
Total hours
—
Total minutes
—
Total seconds
—

Expressing a time span in several units at once helps with contracts, projects, ages and anniversaries. Hours and seconds include the clock times, so the count is exact to the minute.

How to use the Date to Date Calculator

  1. Start date
  2. Start time
  3. End date
  4. End time

Results update as you type, and every field accepts the units shown in its menu.

How it works

Enter the start date and time and the end date and time.

Tips

  • Check whether the end date should be included – event durations usually include it, elapsed time does not.
  • Months have 28–31 days, so “one month” is counted by calendar date, not as 30 days.
  • Use 24-hour time or set AM/PM carefully when entering clock times.
  • Time zones and daylight-saving changes are not applied unless the calculator says so.

Common mistakes to avoid

  • Counting a 30-day month when a calendar month is meant (or the reverse).
  • Forgetting leap years when counting days across February.
  • Mixing decimal hours (7.5 h) with clock time (7:30).

Inputs explained

Field What to enter
Start date A date
Start time A clock time (hours and minutes)
End date A date
End time A clock time (hours and minutes)

What each result means

  • Years = sign([Months])×floor(abs([Months])÷12)
  • and months = sign([Months])×mod(abs([Months]), 12)
  • and days = [End date] – addmonths([Start date], [Months])
  • Total days = [End date] – [Start date] + ([End time] – [Start time])÷24
  • Total weeks = [Total days]÷7
  • Total hours = [Total days]×24
  • Total minutes = [Total days]×1440
  • Total seconds = [Total days]×86400

Formula

Duration = (end date + end time) − (start date + start time)Years, months, days = whole calendar years and months, then remaining days

Worked example

Inputs — Start date: 2026-10-25; Start time: 00:00; End date: 2027-11-29; End time: 00:00.
Results — Years = 1; and months = 1; and days = 4; Total days = 400; Total weeks = 57.14; Total hours = 9,600; Total minutes = 576,000; Total seconds = 34,560,000.

Frequently asked questions

How many days from one date to another?

Subtract the dates; the total days are shown, including any part day from the times.

How many seconds are in a year?

31,536,000 in a common year and 31,622,400 in a leap year.

Why do months vary?

Calendar months have 28–31 days, so "months and days" depends on the actual dates.

What formula does the Date to Date Calculator use?

Duration = (end date + end time) − (start date + start time).

Cite this calculator

Speedy Calculator. (2026). Date to Date Calculator. Speedy Calculator. https://speedycalculator.com/calculators/everyday-life/date-to-date/