Big's Backyard Ultra
2025 Big Dog's Backyard Ultra – Individual World Championship
Ran · this year's race is done.
The World Championship alternates by year between this Individual format (run at Bell Buckle) and a World Team format (run as simultaneous satellite races per country). 2025 was an Individual year.
Race dateOctober 18-23, 2025
Duration6 days
Start7:00am
When363 days ago
First held2011
Who's going to Big's Backyard Ultra?
Free. You can start with nothing.
Free, and always will be. NavRun makes money from race-day planning for runners who want it, never from this.
Ultras change constantly, sometimes the morning of. Always confirm with the race director and the official website before you rely on anything here.
Distance
The Yard – Individual World Championship
Climb
not checked yet
Descent
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High point
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Time limit
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Aid stations
0
Started
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The course
Where it goes
backyard
One 4.1667-mile loop, run every hour on the hour, until only one competitor can complete a lap that no one else can match. All other finishers are recorded as DNF.
The course alternates between two different loops of the same 4.1667-mile length depending on time of day: an 11-hour daytime loop that includes singletrack trail and climbs about 475 feet per lap, and a 13-hour nighttime loop run on paved road that climbs about 100 feet per lap. The daytime/trail loop is considered the more physically demanding of the two. No artificial aids, including trekking poles, are permitted anywhere on course, and no non-competitor (including an eliminated runner) is allowed on the course at all, which as a practical matter rules out pacers and muling.
The race
What this one is
The original backyard ultra: a 4.1667-mile loop run every hour, on the hour, until only one competitor can complete a lap that everyone else fails to match. Every other finisher is recorded as a DNF, however far they went.
Invented in 2011 by Gary "Lazarus Lake" Cantrell on his property in the Short Creek community near Bell Buckle, Tennessee, this race originated the backyard ultra format and has run every October since, except 2015 when it was not held. In 2020, COVID-19 travel restrictions replaced the single Tennessee race with simultaneous satellite national championships; the event has continued in that expanded shape, now alternating each year between a World Individual Championship (run at the original Bell Buckle farm) and a World Team Championship (run as simultaneous races in each competing country, compared by combined team mileage). Harvey Lewis set the men's world record of 108 laps here in 2023; Phil Gore broke it with 114 laps in 2025; Sarah Perry set the current women's world record of 95 laps at the same 2025 race.
Getting in
Getting in
Entry, lottery and what the race asks of you before race day.
- Lottery
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not checked yet
- Lottery opens
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- Lottery draw
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- Field cap
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75
irunfar.com
- Registration
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not checked yet
- Qualifying
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Entry is earned, not purchased or entered via lottery. For the Individual World Championship, national champions (winners of each country's own qualifying/satellite backyard races) and a slate of additional invitees from a rolling international 'At-Large' performance list (drawn from results across the prior roughly two-year qualifying window) fill the field. The 2027 cycle's own published formula is the top 50 national champions plus the top 25 performers on the At-Large list (75 total); the 2025 field size below (75 runners, 40 countries) matches that same total, though the 50/25 split is not separately confirmed for 2025 specifically.
bigsbackyardultra.com
- Minimum age
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not checked yet
- Transfers
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- Deferrals
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Crew access, pacers and drop bags
The rules that shape your day
Anything marked "not checked yet" is a gap in what we hold, never a no from the race.
- Crew allowed
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not checked yet
- Vehicles per runner
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- Pacers
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No
bigsbackyardultra.com
- Muling
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Not allowed
bigsbackyardultra.com
- Drop bags
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not checked yet
- Cupless
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not checked yet
- Course marking
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not checked yet
- Night running
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Yes
irunfar.com
- Dogs
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not checked yet
- Headphones
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not checked yet
- Crew rules
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not checked yet
- Pacer rules
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not checked yet
- Drop bag rules
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not checked yet
- Cutoff philosophy
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There is no course cutoff in the ordinary sense: the clock itself is the format. Each hourly loop starts precisely one hour after the last, with warnings given at 3, 2 and 1 minutes before the bell; every competitor must be in the starting corral and start at the bell, with no late starts; and each loop, including the final one, must be completed within that hour to count. A runner who cannot make it back inside the hour is done.
bigsbackyardultra.com
Same race, other lines
Other distances and other years
What it looks like out there
Somebody has been out there with a camera
the tables say the climb is long. these say what long feels like.
16 people have been out there with a camera or a microphone.
+ 8 more.
These are other people's work and we link straight to them. Watching costs nothing and needs no account.
More of them: every race we hold, on film.
Add to this page
What you know
every one of these is read by a person before it changes anything
Ran this race? Tell the next runner what you know.
Nobody sees it until we have read it. No account, no sign-in.
See something wrong or out of date? Suggest an edit.
This changes nothing on the page on its own. Somebody checks it against the race first.
Seen a course preview or a film of this one? Send it over.
Somebody watches it before it goes anywhere near this page. What we are after is footage of this course, on the ground. If it would be just as true of any other race, it is not this.
Have the GPX? Send us the link.
We want the address of the file the race publishes, not the file. We download it from there so the page can say where the line came from.
Are you the race director? Get in touch and we'll make it right.
We read every one of these and we write back. Every fact here carries the source it came from, and the way a wrong one gets fixed is a person checking it against what you tell us.
Where this came from.
Every fact on this page records its source and when we last checked it: 28 sources for this race. Hover a source link to read the sentence it came from.
27% of what we track for a course is filled in. The rest says "not checked yet" rather than guessing.
Ultras change. We will tell you when this one does.
Cutoffs move, races get postponed, lotteries open and close. We read the race's own sources and record where every fact came from. Put your email in and we will send you what changed, and where we read it.
No account, and nothing to cancel.
What happens to your email. Nothing else. I do not sell it, and I will not send you anything except this race changing. One click gets you out.
I keep this catalog because the information is scattered and hard to trust. Telling you when it moves is the same job.
