Date Calculator
Calculate days between dates, date offsets, business-day estimates, weekend exclusions, and countdowns. The guide explains inclusive counting, Excel functions, month-end behavior, and leap-year edge cases.
Days Between Dates and Business Days
Compare two dates by total days, week equivalent, calendar difference, weekdays, and weekends.
Total days
- Business-day estimate
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- Weekend days
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- Week equivalent
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- Y/M/D difference
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- Difference note
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Add or Subtract Days
Add or subtract days, weeks, months, or years. Month-end dates clamp to the last valid day.
- Result date
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- Japanese era
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Countdown
Change the from date and target date to see remaining or elapsed days.
- Remaining / elapsed
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Date math is half calculation, half definition.
Search intent around date calculation includes days between dates, days from today, days before a deadline, business days, excluding weekends, Excel functions, and countdowns. These are related but not identical. The answer depends on whether you need elapsed days, an inclusive count, a date offset, or a weekday-only estimate.
Inclusive and exclusive counting
From January 1, 2026 to January 31, 2026, the raw difference is 30 days because it measures the distance between the two date boundaries. If a process counts both the start and end dates as occupied days, the inclusive count is 31. The checkbox makes that rule visible instead of hiding it inside the result.
Date offsets and month ends
Adding days and weeks is direct. Adding months and years needs a rule for dates such as January 31. This calculator clamps invalid target days to the last valid day of the target month rather than overflowing into the following month. That behavior is easier to explain for renewals, trial periods, and planning deadlines.
Business days and weekends
The business-day number here is a weekday estimate that excludes Saturdays and Sundays. It does not include public holidays, company holidays, year-end closures, postal delivery schedules, or carrier-specific delivery rules. Use the official provider or your organization’s holiday calendar when those days matter.
Excel function alignment
In Excel, DAYS can calculate a raw date difference, while WORKDAY and NETWORKDAYS-style functions handle weekday logic and optional holiday lists. Results can change when end dates are included, when holiday ranges are omitted, or when a cell is text rather than a real date. Use this page to verify the intended rule before applying a formula to a list.
Countdowns
Countdown mode is for event dates, deadlines, launches, renewals, and reminders. It uses local calendar days in the browser rather than time-of-day precision, which matches how most public countdown messages are written.