WhenMathDeadline Planner
Solve for whichever of start date, deadline, or duration you don't already know, under either plain calendar days or a working-day calendar.
Worked example
Starting Monday, January 4, 2027, a 10-day plan lands on January 14 under plain calendar days, counting straight through any weekends in between. Switch that same plan to a business-day calendar, Monday-through-Friday workweek, instead, and the identical "10" now lands on Monday, January 18, four calendar days later, since weekends no longer count toward the 10 days being measured.
Common mistakes
- Comparing a calendar-day estimate to a business-day deadline as if they used the same units. See the Calendar vs Business Deadline Comparator to check both side by side directly.
- Assuming holidays or blackout dates are excluded automatically. Only the checked workweek pattern is applied here, with no holiday calendar built in.
Limitations
This does not know about holidays or blackout dates unless routed through the Business Days calculators that carry them separately. It plans from the numbers entered directly, not from a contract or policy document.
Frequently asked questions
- Does the start date count as day zero?
- Yes, whichever date serves as the reference point, either the start or the deadline, counts as day zero, and days are counted forward or backward from there.
- Can duration be solved directly from a start and a deadline?
- Yes, selecting the duration option and entering both the start date and the deadline solves for the number of days between them under whichever calendar mode is selected.