Use realistic ranges
Base the shortest and longest times on past results or a pace plan. A single average time hides how much the finish spread matters.
Staggered start planning
Do my race waves finish at the same time?
Enter each wave’s start offset and the shortest and longest finish times you expect. The planner shows every wave’s finish window and how much those windows overlap, so you can adjust start gaps before race day.
Open the plannerMulti-wave finish windows
Plan up to 12 waves
Times are minutes. Start offsets count from event start (T+0). Finish times count from each wave’s own start. The example uses placeholder numbers; replace them with your own assumptions.
The math, explained
How each finish window is calculated
For each wave, the planner computes an earliest and a latest finish time: earliest = start + shortest finish and latest = start + longest finish. Two waves overlap by min(latest A, latest B) − max(earliest A, earliest B) minutes when that value is positive. If the result is zero, the windows only meet at one boundary; if it is negative, they do not share a time.
Example
Wave 1: start T+0:00, finish 2:30 to 4:00 → window T+2:30 to T+4:00
Wave 2: start T+0:20, finish 2:40 to 4:20 → window T+3:00 to T+4:40
Shared time = 4:00 − 3:00 = 60 minutes. Add a scenario start offset to see how moving a wave changes the overlap.
Use it as a planning check
Read the overlap as an input-based check
Compare scenarios
Enter a scenario start for one wave and watch how the total overlap changes. Keep the original plan for reference.
Check with your team
The tool shows time-window overlap only. It does not model crowding, course capacity, medical needs, or official race rules.
Common questions
Race wave planning FAQs
Does this predict how many runners finish at once?
No. It compares the time windows you enter. It does not know how many runners are in each wave, what the finish-time distribution looks like, or where people will be on the course.
Why are start offsets measured from T+0 instead of clock time?
Offsets are cumulative hours and minutes after the event start, so a finish at T+25:00 is 25 hours after start. This avoids confusion about time zones and midnight crossings.
What if two waves only touch?
If the latest finish of one wave exactly equals the earliest finish of another, the planner reports a single shared boundary with zero overlap minutes.
This is a planning calculator for time windows under the assumptions you enter. It is not a prediction of finisher counts, road safety, medical staffing, or compliance with any race or local rules.