Boston Marathon Qualifying Window: Which Races Count
Your BQ only counts if it was run inside the qualifying window for that year's race. The window is a fixed span of dates ending shortly before registration. A marathon run before the window opens does not count, no matter how fast.
How the window works
For a given April race, the BAA accepts qualifying times from certified marathons run over a period of roughly a year and a half ending in the September of registration. That means one fast race can qualify you for more than one Boston, and a strong fall marathon can count for the next spring's registration.
Timing your qualifier
Run your qualifier early in the window if you can, so you have time for a second attempt if you miss your target or the predicted cutoff. Always confirm the exact dates on the official BAA site before you build a season around a race, as windows shift year to year.
Once you have a time, check whether the buffer is likely enough with the predictor.
Frequently asked questions
Can one marathon qualify me for two Bostons?
Often yes. Because the window spans well over a year, a single fast time can fall inside two consecutive registration windows. Confirm the dates each year.
Do old marathon times count?
Only if they fall inside the current qualifying window. Times from before the window opens do not count.