Date Difference Calculator
Calculate the exact time between two dates in years, months, weeks and days. Free, instant and private — everything is computed right in your browser.
How to use the date difference calculator
- Pick a start date. The start date defaults to today — change it to any date in the past or future using the date picker.
- Pick an end date. As soon as both dates are set, the exact difference appears instantly in years, months and days.
- Read the totals. Below the main result you also get the total number of days, full weeks, full months, hours, minutes and seconds — and you can copy the whole summary with one click.
About this tool
This free date difference calculator (also called a days-between-dates calculator or date duration calculator) tells you exactly how much time separates any two calendar dates. It is handy for counting the days until a deadline, working out the length of a project or contract, checking how long you have been at a job, or measuring the gap between two historical events. The calculation is fully calendar-aware: leap years, 28/29/30/31-day months and century rules are all handled correctly.
Everything runs locally in your browser — the dates you enter are never uploaded, stored or logged. Tick the “include the end date” option when both endpoints should count, which is common for booking periods, rentals and event durations.
Frequently asked questions
Does the calculator count both the start and the end date?
By default it counts the time between the two dates, so Monday to Friday is 4 days. Tick “Include the end date” to add one day and count both endpoints — Monday to Friday then becomes 5 days, which is how hotel nights, rentals and event lengths are often counted.
How are months counted when their lengths differ?
The calculator first counts whole calendar months, then the days left over. When a month is shorter than the start day, the month boundary is clamped: January 31 to February 28 counts as exactly 1 month, and January 31 to March 1 counts as 1 month and 1 day. This matches the convention used by most date calculators.
Are leap years handled correctly?
Yes. The tool uses the full Gregorian leap-year rule (divisible by 4, except centuries not divisible by 400), so February 29 in years like 2024 or 2000 is counted, while 1900 or 2100 are correctly treated as common years.
Does daylight saving time affect the result?
No. The difference is computed in whole calendar days, independent of clock changes, so DST transitions never make the result off by an hour or a day. The hour, minute and second totals are simply the day total multiplied out.