How this calculator works
- Step 1Start1 Jan 2026A Thursday.
- Step 2Whole months10 monthsCounted to the same date in each later month.
- Step 3Days left2 daysFrom the last month mark to the end date.
- Step 4Total306 days43 weeks and 5 days.
The calculator counts whole calendar months from the start date, then the days left over. It also turns the period into total days, weeks and months.
Dates are handled as calendar days in the Gregorian calendar, so leap years are included and times or time zones never change the answer.
Worked example: 1 Jan to 3 Nov 2026
- Months
latest same-date month mark on or before the end- Days
end date − that month mark
- SStart date 1 Jan 2026
- EEnd date 3 Nov 2026
- Whole months1 Jan 2026 → 1 Nov 202610 months
- Days left1 Nov → 3 Nov 20262 days
- Total days1 Jan 2026 → 3 Nov 2026306 days
Counting both the first and last dates adds one day: 307 days, or 0 years, 10 months, 3 days.
Counting the end date or not
- Gap between dates306 daysUse for ages, durations and "days since".
- Both dates counted307 daysUse when the first and last days both count, such as leave taken.
The right choice depends on the rule you are applying. A notice or contract usually says whether the first or last day is included; follow its wording.
Month ends and leap years
A month runs to the same date next month, or to that month's last day when the date does not exist.
From 31 Jan 2024, one month reaches 29 Feb 2024, so that period is 0 years, 1 month, 0 days. One more day, to 1 Mar, is 0 years, 1 month, 1 day.
From 29 Feb 2000 to 28 Feb 2001 is 1 year, 0 months, 0 days: in a year without 29 Feb, the anniversary falls on 28 Feb.
Read the result
The headline is years, months and days; the table adds total days, weeks, months and both weekdays.
If the end date is earlier than the start date, the two are swapped and the result says so. The span itself is the same either way.
Assumptions and limits
- Gregorian calendarDates from 1 Jan 1900 to 31 Dec 2100, with leap years.
- Whole daysTimes of day and time zones are ignored.
- Month ruleShort months move the month mark to their last day.
- TodayThe end date starts as the date on your device.
For working days with weekends and holidays removed, use the working days calculator instead.
Related date tools
Counting days is one calendar question. Working days, ages and future dates have their own tools.
To leave out weekends and holidays, use the working days calculator. The age calculator gives an exact age, and the add or subtract dates calculator finds a date some days away.
Common mistakes
Mistake: Counting both dates when only the gap is needed.
Instead: Choose whether the end date counts before you read the total.
Mistake: Treating every month as 30 days.
Instead: Use calendar months, which run from 28 to 31 days.
Mistake: Forgetting leap years over long periods.
Instead: Let the calculator count each 29 Feb in the range.
Checking the method
Every golden case is rechecked with Python's datetime library and a separate month-by-month walk.
The calculator reuses the tested calendar functions from the age calculator. An independent script recomputes every case with Python’s date arithmetic.
Read how we test our calculators, or browse more everyday tools.