Date Difference Calculator: Days Between Two Dates
Free Date Difference Calculator is a free online tool by US AI. How many days between two dates? Pick any start and end date — get the exact difference in days, weeks, and a years/months/days breakdown, plus business-day counts. No signup, works on mobile and desktop.
📖 How to use
- Pick a start date and an end date using the date pickers.
- Optionally check business-days only or include-end-date, then press Calculate Difference.
- Copy the summary for your records. Everything runs in your browser — nothing is uploaded.
✨ Why use this tool?
US AI's free date difference calculator uses DST-safe UTC math for exact results. It is fast, private and 100% free forever — nothing you enter ever leaves your browser.
- Project deadlines — count the working days left until a milestone, excluding weekends.
- Tenure & notice periods — measure exact service length between a joining date and a leaving date.
- Age in days — see how many days, weeks or months you or a loved one have lived.
- Event countdown — find out how many days remain until a wedding, exam, or travel date.
❓ Frequently asked questions
How do I find the number of days between two dates?
Pick a start date and an end date in the date pickers, then press Calculate Difference — the tool shows the exact number of days between them instantly, plus weeks and a years/months/days breakdown.
Does it count business days or calendar days?
Both. By default you get calendar days; check the business-days-only option to exclude Saturdays and Sundays and see how many working days fall between your two dates.
Are leap years and daylight-saving changes handled?
Yes. The calculator uses DST-safe UTC math, so leap years (including February 29) and daylight-saving time shifts never distort the result — the count is exact down to the day.
Can I include the end date in the count?
Yes — tick the include-end-date option and the final day itself is counted. Leave it off for the standard exclusive count (end date minus start date).
What result formats do I get?
Every calculation returns total days, total weeks, a years/months/days breakdown, and — with the option enabled — the number of business days between your dates.
Is my data private?
Completely. Everything runs in your browser — no dates you enter are uploaded, stored or shared anywhere. It is free forever with no signup.