Between dates
The inclusive end-day toggle adds or removes one calendar day from the total. When a holiday skip list is active, listed holidays move from Weekdays into the Holidays row; the total day count does not change.
Between dates or add / subtract days
Day Counter Calculator: Count Days Between Dates, or Add and Subtract Days from a Start Date
Count days between two dates with separate totals for weekdays, weekends, and holidays, or add or subtract days from a start date. Turn on Business days only in Add / subtract when you need working-day steps; optional US, UK, Canada, or custom holiday skip lists apply in both modes. Also walks through the Doomsday Rule step by step to show which weekday your start date falls on. Inputs stay in your browser.
By Jeff Beem
Updated
01
Mode
Holidays
Day count
1 days
Weekdays: 0
Weekends: 1
Start: Sunday, July 12, 2026
End: Sunday, July 12, 2026
02
Reference
Add / subtract
With Business days only, each counted day after the start must be a weekday and not on your holiday skip list when a list other than None is selected. With the skip list on None, only weekends are skipped. Calendar-day mode adds or subtracts raw days on the calendar.
Doomsday rule
Anchor weekdays on 4/4, 6/6, 8/8, 10/10, and 12/12, then apply the century anchor and year formula on the last two digits of the year.
Formula (yy = last two digits of year)
The walkthrough below uses your current start date.
Weekday walkthrough
Steps for July 12, 2026:
1. Century anchor
For the 2000s, century anchor is Tuesday (d = 2)
2. Year (yy = 26)
a = 2, b = 2, c = 0
3. Doomsday for 2026
f = 6 → Saturday. Nearest doomsday in Jul: 7/11. Offset 12 − 11 = 1 → Sunday.
Reading the breakdown
Pick a mode first. Between dates fixes a start and end and shows total days plus weekdays, weekends, and (when you pick a skip list) holidays. Add / subtract moves one start date forward or back by N days. Business days only appears only in Add / subtract: leave it off for calendar days (90 calendar days from signing), turn it on when N should count Mon–Fri and skip listed holidays. The inclusive-end toggle applies only in Between dates.
Example: March 1–31, 2026 (inclusive end day on)
In Between dates mode, set start March 1, 2026 and end March 31, 2026, leave Include end day in count checked, and leave the holiday skip list on None. The panel shows 31 total days, 22 weekdays, and 9 weekend days. Turn the inclusive toggle off and the total drops to 30 because the end date is excluded from the count (the span runs through March 30).
Example: 10 calendar days vs 10 business days (March 3, 2026)
In Add / subtract mode with start March 3, 2026 (Tuesday) and 10 days: leave Business days only off and Add → Saturday, March 13 (10 calendar days later). Enable Business days only with the skip list on None → Tuesday, March 17 (10 weekdays after the start, weekends skipped). Same mode, same number; the checkbox switches calendar math from business-day math.
Skip list moves days between rows, not the total
In Between dates mode, picking a skip list does not remove days from the total count. Federal Mondays move from Weekdays into Holidays so the three rows still sum to the same total. In Add / subtract with Business days only, the same list tells the counter which dates to skip while it advances.
Day Counter Calculator: days between dates and business-day counts
Count a date range with separate weekday and weekend totals, or add and subtract working days from a start date with optional holiday lists.
What this calculator does
This day counter tallies days between two dates and splits the span into weekdays, weekends, and holidays when you pick a skip list. In Between dates mode you fix start and end, choose inclusive or exclusive counting, and read the breakdown in the dark results panel. In Add / subtract mode you move a start date forward or backward by a day count, optionally counting business days only so weekends and skipped holidays do not advance the counter. US federal, UK England and Wales, Canada federal, and custom YYYY-MM-DD lists are supported. It does not track hours, minutes, or partial days. The Reference section walks through the Doomsday Rule step by step for the start date you entered. For rolling months and years on one anchor, use the Date Calculator. For two birthdays and an age-style gap, use the Age Difference Calculator. Everything runs locally in your browser.
How the math works
Total days come from the calendar span between midnight anchors, with the inclusive-end toggle deciding whether the end date itself counts as a full day. When the holiday skip list is None, weekday and weekend totals use a closed-form split from the start weekday and span length. When a skip list is selected, the tool walks day by day so listed holidays land in the Holidays row instead of Weekdays while the total day count stays the same. In Add / subtract mode with Business days only, it moves one calendar day at a time, skips Saturdays and Sundays, and skips dates on your skip list (when not None) until the counter reaches the number you typed. The start date is not counted as the first business day; counting begins on the next calendar day.
The Doomsday Rule walkthrough uses a century anchor and modular arithmetic on the year’s last two digits to name the weekday. It is a cross-check on the weekday name, not part of the day-count totals.
Calendar days vs adding business days
Calendar days count every date in the window, which is what many visa, lease, and “within 30 days” rules mean. Adding or subtracting business days is for “ten working days from receipt” language: weekends do not advance the counter, and dates on your holiday skip list do not either when a list other than None is selected. Use Between dates when both endpoints are fixed; use Add / subtract with Business days only when you need a landing date after N working days forward or back.
Inclusive end day: the usual off-by-one
March 1 through March 31 inclusive is 31 days because both March 1 and March 31 count. Turn inclusive end off and the same pair reports 30 days because the end date is treated as exclusive. HR and project trackers disagree on this all the time, so set the toggle to match how your deadline was written.
The Doomsday Rule
The Doomsday Algorithm finds the weekday of any date from anchor dates that share a weekday within a year (4/4, 6/6, 8/8, and so on) plus a century anchor. The Reference section on the calculator page shows the formula and runs the arithmetic for your current start date so you can verify Tuesday vs Wednesday without a second tool.
Day Counter Calculator FAQ
How do I count days between two dates?
Use Between dates mode. Pick start and end. Turn on Include end day in count when both boundary dates should count (most lease and notice language). The panel splits the span into total days, weekdays, weekends, and holidays when a skip list is active.
How do I add or subtract business days?
Switch to Add / subtract, enter a start date and a day count, enable Business days only, and choose Add or Subtract. The counter moves one calendar day at a time, skipping weekends and, when you pick a holiday skip list other than None, any listed holiday dates. Ten working days after Tuesday, March 3, 2026 lands on Tuesday, March 17, 2026 with the skip list on None (weekends only).
What is the difference between weekdays and business days?
Weekdays are Monday through Friday inside the span shown in the results panel. The panel does not show a separate “business days” total; it lists weekdays, weekends, and (when a skip list is selected) holidays as separate rows that add up to the day count. In Add / subtract mode, Business days only uses that same skip list to pick a landing date after N working days, skipping weekends and listed holidays.
How do I exclude custom holidays?
Under Holidays → Skip list, choose Custom dates... and paste YYYY-MM-DD values separated by commas or new lines. In Between dates mode those dates appear in the Holidays row instead of Weekdays. In Add / subtract with Business days only, they are skipped while the counter runs.
What is the Doomsday Algorithm?
John Conway’s Doomsday Rule finds the weekday of any date from a century anchor and a short formula on the year’s last two digits. The Reference block below shows the formula and a step-by-step walkthrough for your start date, useful when you want to sanity-check the weekday name without trusting the calendar picker.
Time & Date Reference Note
Informational Use: These tools use standard date/time algorithms and your browser’s timezone data (IANA). Results are intended for general reference and planning only.
Verification Recommended: Time zone rules and daylight saving changes vary by region and year. For critical scheduling, payroll, or legal deadlines, confirm results with official sources.
Local Verification: Always confirm times, dates, and business-day counts with official sources or qualified professionals when stakes are high.
© 2026 CalcRegistry Reference Last Logic Update: July 2026Free Online Utility Tools