Date Difference Calculator
Count the days, weeks, and months between two dates.
That's 0 years, 11 months, and 30 days.
Use on any page (bookmarklet)
Want Date Difference Calculator without leaving the page you're on? Drag the button below to your bookmarks bar, then click it on any website to open Date Difference Calculator right there — it runs entirely in your browser.
Use responsibly: a bookmarklet runs on whatever page you click it on. Avoid sensitive sites such as online banking, payment, or healthcare pages — you run it at your own risk. Everything is processed locally and no data is sent anywhere. See our Terms.
- Show your bookmarks bar if it's hidden — Ctrl+Shift+B (⌘+Shift+B on Mac).
- Drag the button above onto the bookmarks bar.
- Open any website and click the bookmark — the Date Difference Calculator panel appears in the top-right corner. Use ✛ to move it between corners, or ›/‹ to tuck it against the edge and pull it back out.
- Click the bookmark again (or the ✕) to close it.
Note: a few sites with strict security policies may block bookmarklets.
Examples
Across a full year
Input
2025-01-01 → 2025-12-31
Output
364 days · 52 weeks · 0y 11m 30d
A short span
Input
2025-03-01 → 2025-03-15
Output
14 days · 2 weeks
About this tool
This free online date difference calculator counts the time between two dates. Pick a start and end date and instantly see the total days, the number of weeks, and a clean years / months / days breakdown. Everything runs in your browser with no upload.
How to use
- Choose a start date.
- Choose an end date.
- Read the total days, weeks, and the calendar breakdown.
Inclusive or exclusive: decide before you quote a number
Almost every argument about a date difference comes down to this. From Monday to Friday is 4 days if you count the gaps between them, and 5 days if you count the days themselves. Neither is wrong — they answer different questions.
- Exclusive (the span) — what this calculator shows. Right for durations, notice periods, and “how long until”.
- Inclusive (both ends) — add one to the total. Right for “how many days am I on site”, conference days, and most leave requests.
Hotels use a third convention entirely: they charge by nights, which matches the exclusive count. A Monday check-in and Friday check-out is four nights and five days of your time.
Calendar days versus working days
This tool counts calendar days, weekends and holidays included. Contracts and legal notice periods frequently specify business days instead, and the gap widens fast — 30 calendar days is about 21 working days, so a deadline read the wrong way can be more than a week out. As a quick conversion, divide by 7 and multiply by 5, then subtract any public holidays that fall in the range. Which holidays count depends on jurisdiction, which is why no calculator can answer this for you universally.
Leap years and uneven months
The count walks the real calendar, so 29 February is included whenever the span crosses one. The rule is less simple than “every four years”: century years are skipped unless they divide by 400, which is why 1900 had no 29 February and 2000 did. The same unevenness explains why the years-months-days breakdown can differ for identical day totals — a 60-day span starting in January covers two short months, while one starting in July covers two long ones.
Common uses
Counting down to a deadline or event, measuring project duration, tracking time since a milestone, checking notice periods and contract lengths, and working out how long an account or subscription has run. To move a date forward or back by a set amount instead, use date add & subtract; for a difference expressed as an age, the age calculator handles the birthday edge cases.
Frequently asked questions
How do I count the days between two dates?
Pick a start and end date and the calculator shows the total number of days between them, plus weeks and a years/months/days breakdown.
Does it include both the start and end dates?
It counts the span between them, not the days themselves. Monday to Friday is 4 — you cross four midnight boundaries — even though five days are involved if you're counting the days you'll be somewhere. Add one for inclusive counting. This distinction is behind most disputes about deadlines, hotel nights, and leave requests, so it's worth deciding which you mean before quoting a number.
Why does my spreadsheet give a different answer?
Usually because it's answering the inclusive-versus-exclusive question differently, or because DATEDIF and similar functions truncate partial months in ways that surprise people. Spreadsheets also store dates as serial numbers from a fixed epoch, which is why some show a phantom 29 February 1900 — a bug preserved from Lotus 1-2-3 for compatibility.
Are leap years handled?
Yes. The day count walks the actual calendar, so 29 February is included whenever the span crosses one. A year is a leap year if it divides by 4, except centuries, unless they divide by 400 — which is why 1900 was not a leap year and 2000 was.
Does this count business days?
No — it counts calendar days, including weekends and holidays. As a rough conversion, calendar days divided by 7 and multiplied by 5 gives you working days, but any real answer depends on which public holidays apply, and those differ by country and sometimes by region.
How are months and years counted in the breakdown?
Complete calendar years first, then complete months, then the leftover days — the way you'd naturally say "one year, two months, and three days". Because months have different lengths, the same total in days can produce different breakdowns depending on where in the year it falls, which is expected rather than an error.
Does the order of the dates matter?
No. If the end date is earlier than the start date, the absolute difference is used so the result is always positive.
Is a day always exactly 24 hours?
Not in a timezone that observes daylight saving. The days on which clocks shift are 23 or 25 hours long, so a span measured in hours won't always divide evenly into the day count. This calculator works in whole calendar days, which is what you want for deadlines and durations and avoids the problem entirely.
Is my data uploaded anywhere?
No. The calculation runs entirely in your browser with no upload.
Learn more
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