Countdown Days Calculator
Count elapsed days, approximate workdays and rest days between two dates.
Last updated · View algorithm, constants and default inputs (JSON)
Results
About this calculator
Split a date range into elapsed days, workdays and rest days. Five-, six- and seven-day schedules use standard weekday patterns; one-to-four-day schedules are proportional estimates because specific workdays are not selected.
Worked example
calculated with the default values below
Start date 2026-10-31 · End date 2026-12-31 · Public holidays in the period 2 days · Working days per week 5 · Working hours per day 8 hours Total days 61 days · Working days 42 days · Non-working days 20 days · Working hours available 336 hours · Weeks 8.7 weeks · Months 2.0 months · Whole weeks of work 8.4 weeks
General background references
Disclaimer
These calculators give general date results. Public holidays, working-day conventions and time-zone rules are set locally and change, so confirm against the official calendar for anything legally or contractually binding.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
D = |round((E − S) ÷ 86400000)|; W = Σ w_k − H (k = 0..D)
- S
- Start date
- E
- End date
- p
- Working days per week
- w_k
- Working-day indicator: w_k = 1 on a working day, else 0
- H
- Holidays to subtract
- h
- Hours per working day
Elapsed calendar-day difference excludes the start date; weekday counts include both endpoints. Five days counts Monday–Friday, six excludes Sunday, seven counts all dates, and one to four proportionally scale the Monday–Friday count. Holiday input is a count, not a dated calendar.
Frequently asked questions
How are workdays estimated for a nonstandard workweek?
For a five-day week the calculator counts Monday through Friday; for six days it excludes Sunday, and for seven it counts every date. A one-to-four-day week scales the Monday–Friday count proportionally because no specific workdays are selected. Enter the number of public holidays in the range; exact holiday dates are not modeled.