The Short Answer
Both are multiday formats, but they are built on opposite rules. The 6-day race fixes the time and lets you decide everything else. The backyard ultra fixes the distance per hour and takes every other decision away from you. Our 6-day race guide and backyard ultra guide cover each format in full; this page puts them side by side.
Head-to-Head Comparison
| Factor | 6-Day Race | Backyard Ultra |
|---|---|---|
| Clock | Fixed: 144 hours | Open-ended; one start every hour |
| Course | Track or short measured loop, usually 400 m to 2 km | One 6.706 km (4.167 mi) loop, repeated |
| Pacing | Entirely self-directed | Fixed: finish the loop within the hour, every hour |
| Sleep | Planned blocks or naps, adjusted daily | Only in the minutes left before the next start |
| Race ends when | The clock reaches 144 hours | Only one runner completes a loop; everyone else has a DNF |
| Winner | Most distance | Last person standing |
| Competition style | Against yourself and the clock | Head-to-head elimination |
| Distance outcome | Strong amateurs 500 to 700 km; top marks above 1,000 km | 6.706 km per hour completed; 24 yards = 100 miles |
| Time commitment | A full week plus travel | Most entrants are out within 12 to 30 hours; the winner may run for days |
Which Suits You?
Choose the 6-day race if you want autonomy: you set the run-walk rhythm, the meal times, and the sleep schedule, and you can recover from a bad night by taking a longer rest. Choose the backyard ultra if you want structure and direct competition: a short loop you know by heart, a whistle every hour, and a race that is decided against the people beside you rather than against a distance total.
The Mental Difference
A 6-day race gives you freedom, which sounds easier until you realize every major decision is yours. You decide when to sleep, when to stop for foot care, when to eat, and whether a bad hour should become a longer break. That freedom rewards runners who can think clearly while depleted and avoid turning small problems into lost half-days.
A backyard ultra removes that freedom. The clock tells you when to start, the loop tells you how far to go, and the field tells you whether the race is still alive. The hard part is psychological repetition: you recommit every hour with no visible finish line. Runners who like structure often find this oddly calming. Runners who need flexibility feel trapped by it.
Which Should Be First?
For most runners, the backyard ultra. Events are more numerous, entry is cheaper, and the practical commitment is smaller: the large majority of the field misses a start within the first day or two and goes home. You can enter with a personal yard goal, say 12 or 24 yards, and treat the race as a supported long run with a built-in stopping rule. A 6-day race asks for a week away, a personal support area, a crew or a solid solo system, and a sleep plan you have rehearsed.
Neither format is a first ultra. Run a 50K and then a 24-hour race first; both teach the fueling, foot care, and night-running skills the multiday formats assume you already have. Whichever you choose, write down your stopping conditions before the start. The short backyard loop does not make an open-ended effort safe, and the fixed 6-day clock never obliges you to continue when warning signs appear.
Sources
- Global Organization of Multi-Day Ultramarathoners — 6-day world records and record progressions (record keeper for the 6-day format)
- Big's Backyard Ultra — official backyard ultra rules and record table (119 yards by Phil Gore, June 2025; checked September 14, 2026)