Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Count work days and full work weeks between two dates.
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This calculator estimates the total work days and full work weeks between two dates, given a configurable work-week length (5 days by default) -- useful for rough project-duration planning when you know a start and end date but need to know how many actual work days fall in between.
Enter a start date, end date, and work days per week (default 5, for Monday-Friday). The result shows total calendar days, total work days, full work weeks, and leftover work days.
Total work days is estimated proportionally: (total calendar days / 7) x work days per week, rounded to the nearest whole day -- a fast approximation rather than a day-by-day weekday count (see the Business Days Calculator for an exact count that also excludes weekends specifically).
January 5-18, 2026 (14 calendar days) at 5 work days/week: 10 total work days (2 full work weeks).
For an exact weekday count that specifically excludes Saturdays and Sundays, use the Business Days Calculator instead.
Take a project running from March 2 to March 29, which is 28 calendar days including both end dates. At 5 work days per week, the estimate is 28 divided by 7 times 5, exactly 20 work days, or 4 full work weeks with none left over. Now take a 20-day span at 4 work days per week: 20 divided by 7 is about 2.857, times 4 gives 11.43, which rounds to 11 work days. That is 2 full work weeks with 3 leftover days. The dates here are illustrative only.
The calendar-day figure is inclusive of the start date and the end date. A range from Monday to the following Sunday is therefore 7 days, not 6. This is handy for schedules where both boundary days are working days, but if your plan treats the end date as the day after the last work day, subtract one from the end date before entering it.
Because the tool multiplies the calendar-day count by work days per week over 7 and then rounds, short spans can be off compared with an actual count. A range covering only Saturday and Sunday is 2 calendar days and gives 2 divided by 7 times 5, which is 1.43, rounding to 1 work day, even though a real count of weekdays would be zero. In the other direction, a Monday to Friday span of 5 days gives 3.57 and rounds to 4, though the real answer is 5. The proportional method works best over spans of several weeks, and its accuracy improves as the span gets longer.
Enter the number of days per week you actually work, from 1 to 7. A compressed schedule of four 10-hour days is 4, a standard office schedule is 5, and a retail schedule with rotating days off can be entered as an average. The tool does not know which days of the week are worked; it only uses the count, so it cannot distinguish a Monday to Thursday schedule from any other four-day pattern.
Public holidays, vacation and company shutdowns are not subtracted. If your project window includes them, remove those days from the total afterwards. The output is also a count of days, not hours, so multiply by your daily hours to estimate effort, and treat the final figure as a planning estimate rather than a commitment for contracts or payroll.
The Business Days Calculator counts actual weekdays day-by-day, always excluding Saturday/Sunday specifically. This tool estimates proportionally for any work-week length you specify (not just a Mon-Fri pattern), which is a faster approximation but less exact for irregular schedules.
Yes -- set "work days per week" to any value from 1-7 to match your schedule.
Because it's a proportional estimate over the exact calendar-day span, which usually doesn't land on an exact number of full weeks.
The tool estimates proportionally from the calendar-day count rather than checking which weekdays are in the range, so tiny spans can round to a value that a real count would not give.
Yes. The calendar-day total is inclusive of both dates, so a Monday to Sunday range counts as 7 days.
No. Subtract any public holidays or shutdown days yourself from the work-day total.
Reference: U.S. Department of Labor