| What it means | Started but didn't finish the race |
| Causes | Injury, illness, GI issues, exhaustion, cutoffs |
| Common in | Long & mountainous ultras |
| Related | Missing a cutoff time |
DNF stands for ‘Did Not Finish’ — when a runner starts a race but drops out before completing it, whether by choice or by missing a cutoff. Common in long and mountainous ultras, a DNF can result from injury, illness, stomach problems, exhaustion, or weather. It’s a normal part of pushing limits in ultrarunning, and learning from a DNF is part of the sport.
Part of the game
Often caused by missing a cutoff time or hitting the bonk in ultrarunning.
Frequently asked questions
What does DNF mean?
DNF means 'Did Not Finish.' It's recorded when a runner officially starts a race but stops before reaching the finish line, either by voluntarily dropping out or by being pulled for missing a cutoff time. It's distinct from DNS ('Did Not Start') and is common in demanding ultramarathons.
Why do runners DNF?
Reasons include injury, illness, severe gastrointestinal distress, dehydration or fueling failures (the bonk), hypothermia or heat illness, equipment problems, or simply running out of time against a cutoff. In tough mountain ultras, DNF rates can be high, since the conditions and distances push runners to their limits.
Is a DNF a failure?
Not really — experienced ultrarunners view DNFs as part of the sport and sometimes the wise, safe choice when continuing risks serious harm. Many learn valuable lessons about pacing, fueling, and gear from a DNF that help them finish next time. Knowing when to stop for safety is a mark of good judgment, not failure.
Sources
- Race terminology — American Trail Running Association
- Ultra racing — The Mountaineers