Date Difference Calculator
Count the time between two dates.
Results update as you type.
How it works
A date difference calculator measures the span between two calendar dates and expresses it as a number of days, then translates that figure into weeks, months and years for a sense of scale. It converts each date to a running day count, takes the absolute gap between them, and reports the result so you never have to tally the uneven lengths of the intervening months by hand. Getting the interval right matters whenever a deadline, an anniversary or a contract term depends on it. Counting on your fingers across month boundaries is where errors creep in, especially over spans that cross a leap year or several year-ends, and a single miscounted day can mean a missed filing or a mispriced interest period. The day count is exact because it works from the real calendar rather than assuming every month is thirty days, while the weeks, months and years are deliberately labelled approximate since months genuinely vary in length. Project managers sizing timelines, lawyers computing notice periods, and anyone counting down to an event lean on a date difference calculator to replace guesswork with a figure that holds up.
days = |end − start| in whole days; weeks/months/years derived from days
Each date is converted to a serial day number, and the difference between those two numbers is the exact day count — no month-length assumptions enter. Weeks come from dividing days by seven; months and years use average lengths (30.44 and 365.25 days). This works because a continuous day index absorbs every leap day automatically, so only the derived units carry rounding.
Source:Standard calendar arithmetic
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter start date and end date.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Days updates instantly as you type — no button to press.
Frequently asked questions
Does it include both the start and end date?
It counts the days between the two dates, so the start date itself is not added to the total. If you need both endpoints counted inclusively, for example to bill every day a room was occupied, add one to the result. Whether to count inclusively depends on your purpose, which is why the calculator reports the plain interval.
How many days are between two dates exactly?
The calculator subtracts one date's serial day number from the other, giving an exact count that already includes any leap days in between. This is more reliable than multiplying months by thirty, which drifts because months range from 28 to 31 days. The figure shown is the true number of calendar days separating the two dates.
Are the months and years figures exact?
No, and they are labelled approximate for that reason. The day count is precise, but months and years are derived using average lengths of about 30.44 and 365.25 days. A gap of 364 days reads as roughly eleven months even though it spans nearly a full calendar year, so treat those figures as a sense of scale rather than a calendar-accurate breakdown.
Does the order of the dates matter?
No. The calculator uses the absolute difference, so entering the later date first gives the same result as entering it second. This means you never have to worry about which date is earlier. If you need a signed direction, note it yourself, but for measuring the length of an interval the order is irrelevant.
Does it count leap years correctly?
Yes. Because each date is turned into a continuous day number before subtracting, any 29 February falling inside the range is included automatically. There is no separate leap-year adjustment to remember and no risk of double-counting. A span from early 2024 to early 2025, for instance, correctly includes the extra day from 2024's leap year.