Date Calculator
Find the difference between two dates, add/subtract time, or count down to an event.
Days between two dates
Three ways to work with dates
The Difference tool counts the exact number of calendar days between two dates by converting both into timestamps and subtracting, which automatically accounts for leap years, varying month lengths, and daylight-saving shifts without you needing to think about any of it. It then converts that day count into weeks, and approximate months and years, using standard averages (30.44 days per month, 365.25 days per year) since months and years aren't fixed lengths.
The Add/Subtract tool moves a start date forward or backward by a chosen amount — days, weeks, months, or years. Adding months or years is handled calendar-aware rather than as a fixed number of days, so adding one month to January 31st correctly lands on the last valid day of February rather than overflowing into March. This mode is commonly used for calculating deadlines, contract renewal dates, warranty expirations, or "90 days from today" type questions.
The Countdown tool runs live, updating every second, and shows how much time remains until (or has passed since) a target date — handy for tracking an upcoming event, deadline, or anniversary right on the page rather than doing mental math repeatedly. If the target date has already passed, the counter automatically switches to show elapsed time instead, labelled accordingly, so the same tool works whether you're counting up or down.
Frequently asked questions
Does the days-between calculation include both the start and end date? By default it counts the number of full days that separate the two dates, the same way you'd count nights between a check-in and check-out — add one if you need an inclusive day count instead.
Can I subtract time instead of adding it? Yes, the add/subtract tool works in both directions — enter a negative number of days, or use the subtract option, to find a date that far in the past.
What's the countdown tool useful for? It's built for tracking toward a specific future date — a deadline, trip, or event — and updates the remaining days, hours, minutes, and seconds continuously while the page is open.
Worked example
Adding 90 days to May 1st lands on July 30th — useful for calculating a 90-day payment term, a visa validity window, or a product return deadline.
Does the calculator account for leap years? Yes — it uses the actual calendar, so a date range crossing February in a leap year correctly counts the extra day (February 29th).
Can I calculate the number of business days instead of calendar days? The core tool calculates calendar days; to estimate business days, subtract roughly 2 days per weekend within the range, or use the result alongside a calendar to exclude specific holidays.