Calculation details
Planning estimate only, not financial, tax, or legal advice. Verify assumptions and current rules before making decisions.
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Use this result
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What does this calculator estimate?
A days-between-dates calculator counts the exact number of days, weeks, and weekdays between two dates. Pick a start and end date to see the gap.
- Days = calendar difference at midnight
- Weekdays exclude Saturday and Sunday
- End date must be after the start date
How date gaps are counted
Date math counts the exact number of 24-hour periods between two calendar dates. The result is useful for deadlines, billing periods, interest accrual, and planning.
Limitations to watch for
The tool counts calendar days, not business days — weekdays exclude weekends but not holidays. The end date must be after the start date. Time-of-day components are ignored (both dates are taken at midnight).
How to use it in practice
Use it to compute notice periods, loan terms, or project durations. For business deadlines, subtract holidays yourself. Double-check inclusive vs exclusive counting: 'due in 30 days' often means 30 days from today.
['Pick a start date.', 'Pick an end date after the start.', 'The tool returns days, weeks, and weekdays.']
How this calculator works
Formula
Days = (end date − start date) ÷ 86,400,000 ms per day, computed on calendar dates at midnight. Weeks = days ÷ 7. Weekday count iterates the calendar days between the dates, excluding weekends.
Worked example
From January 1 to February 1, 2026: 31 days = 4.4 weeks.
Assumptions to verify
- Both dates are interpreted at local midnight.
- The end date is later than the start date.
- Weekday count excludes Saturdays and Sundays only.
Frequently asked questions
How do I count days between two dates?
Subtract the earlier date from the later one in calendar terms — the tool does this exactly. Jan 1 to Feb 1 is 31 days.
What is the difference between calendar and business days?
Calendar days count every day; business days exclude weekends (and often holidays). The tool shows calendar days plus a weekday count.
Is the end date included?
The tool counts the gap between the dates (end minus start). If you need inclusive counting, add one.
Why does the tool reject equal dates?
The end date must be after the start for a positive gap. If they're equal, the gap is zero.
How many weekdays are between two dates?
Count the days that fall on Monday–Friday. The tool iterates the calendar to compute this.
Does this account for holidays?
No — holidays are jurisdiction-specific. Subtract them manually for business timelines.
What about leap years?
The calendar handles leap years automatically — Feb 29 is counted when it falls between the dates.
Cite this tool
BoringToolsKit. “Days Between Dates Calculator.” boringtoolskit.com/days-between-dates-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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