Total days
N = end date − start date (+ 1 if the end date is included)
Date difference calculator
Compare two dates and get the exact gap in years, months and days, the total number of days and the equivalent in weeks, with an option to include the end date.
- Clipboard
Select two valid dates.
Exact duration
- Total days
- In weeks
Was this tool useful?
How does this tool work?
This calculator measures the time between two dates: the gap in years, months and days, the total number of days and the equivalent in weeks and days. Use it for the length of a contract, a stay, a probation period or a project, for length of service, or for the time elapsed since an event. The order of the dates does not matter: if the end date comes first, the tool swaps them.
By default the tool counts like a stopwatch that starts on the first day and stops at the start of the last one: from Monday to Tuesday is 1 day. This is the convention of most date calculations (subtracting two dates in a spreadsheet, ISO 8601 durations).
Tick “Include the end date” when both dates count, as for a rental, a holiday or a school year “from 1 September to 30 June inclusive”: the tool then adds 1 day, which amounts to measuring up to the day after the end date.
The breakdown into years, months and days follows the calendar: the tool counts whole months from the start date, then the remaining days. If the start day does not exist in a month (the 31st in a 30-day month, 29 February in a common year), the whole month is reached on the last day of that month. The total number of days is exact and includes every 29 February crossed.
How to use this tool
Enter the start date
Type the date as month/day/year or pick it from the calendar.
Enter the end date
The order does not matter: the tool always returns a positive gap.
Decide whether the end date counts
Tick the option for an “inclusive” period, then read the duration, the total days and the weeks.
Working out the gap between two dates
The total in days and the calendar breakdown answer two different questions: “how many days?” and “how many years, months and days?”.
Weeks and days
weeks = ⌊N ÷ 7⌋; remaining days = N − 7 × weeks
Whole months
M = largest integer such that start + M months ≤ end; years = ⌊M ÷ 12⌋
- N
- total number of days between the two dates
- M
- number of complete months within the period
Converting days into months by dividing by 30 or 30.44 is only an approximation; the calendar breakdown uses the real length of each month.
Use cases
Length of a contract or assignment
Find the exact length of a fixed-term contract, an internship or a probation period between its start and end dates.
Length of service or ownership
Measure service between a hiring date and a leaving date, or how long an asset was held between purchase and sale.
Stays and rentals
Count the days of a stay abroad, a rental or a custody period, end date included.
Time since an event
See how many days, weeks or months have passed since a past date: a wedding, a move or the founding of a company.
Examples
A school year, both dates included
Without the option the result is 9 months and 29 days, i.e. 302 days: the gap does not count 30 June itself.
Input
From 1 September 2026 to 30 June 2027
End date includedResult
10 months, 0 days
303 days · 43 weeks and 2 daysA simple gap
Five whole months lead to 15 June; from 15 June to 1 July there are 16 days left.
Input
From 15 January 2026 to 1 July 2026Result
5 months, 16 days
167 days · 23 weeks and 6 daysTips and best practices
- For a legal or contractual deadline, check the counting rule that applies (first day excluded, business days only, roll-over to the next working day): this calculator counts calendar days.
- To count weekdays only, use the business days calculator; to find the date reached after a duration, use the add or subtract time from a date tool.
- For an age, the age calculator uses the same method and adds the date of the next birthday.
- The calculation link keeps both dates and the option you chose, so the person you send it to sees exactly the same result.
Sources and references
- Claus Tøndering, The Gregorian Calendar (opens in a new tab), Calendar FAQPage in English
- ISO — ISO 8601 date and time format (opens in a new tab)Page in English
- TC39, Temporal.PlainDate (opens in a new tab), Temporal documentationPage in English
Frequently asked questions
How many days are there between two dates?
Enter both dates and the total number of days appears straight away. By default it is the difference between the dates (from the 1st to the 2nd = 1 day). Tick “Include the end date” to count both ends (from the 1st to the 2nd = 2 days).
Should I include the first and last day?
It depends on what you are measuring. For elapsed time (age, length of service, an interval) the last day is not counted. For a period whose days are all used, such as a rental, leave or a stay, include it.
How are months of different lengths counted?
Months are counted date to date: from 15 January to 15 February is 1 month, whether February has 28 or 29 days. When the date does not exist (31 April), the month is reached on the last day of the month, then the remaining days are added.
Are leap years taken into account?
Yes. The total is calculated on the Gregorian calendar: from 1 January 2028 to 1 January 2029, for example, there are 366 days because 2028 is a leap year.
Can daylight saving time change the result?
No. The tool works with dates without times, so a day is always a day, even when the period crosses a clock change.
Can I calculate a duration in hours or minutes?
This calculator works to the day. For the gap between two times or two timestamps, use the time duration calculator.
Related tools
Keep going with these tools
Tools similar or complementary to this one.
Similar tools
Count the business days between two dates and shift a date by a number of working days, for a Monday–Friday or other working week.
Dates & timeFeaturedUse this tool
Add or subtract days, weeks, months or years from a date and get the resulting date with its day of the week.
Dates & timeUse this tool
Calculate an exact age in years, months and days from a date of birth and any reference date.
Dates & timeFeaturedUse this tool
Read next
GuideBest practicesIntermediate
How to calculate business hours between two dates and times
Understand the difference between business days, business hours and working time, then calculate useful time inside opening hours.
8 September 20262 min
GuideConcepts and technologiesBeginner
Date calculations: differences, deadlines, business days and calendar arithmetic
Learn how to calculate a difference between dates, add or subtract a duration, count days to a deadline, and distinguish calendar days from business days.
28 August 20264 min
GuideBest practicesBeginner
Date and time calculations: a practical guide
Date differences, durations, business days, ISO weeks, recurrences and formats: choose the right date and time calculation.
7 September 20262 min
GuideConcepts and technologiesBeginner
Durations and time: calculate, convert and handle midnight crossings
Understand the difference between a clock time and a duration, calculate intervals between times, and convert seconds, minutes, hours, days and weeks.
28 August 20263 min