Guide
How long is a backyard ultra lap?
A backyard ultra lap — a yard — is 6.706 kilometres, or 4.167 miles. It is the same at almost every race in the world, and the number is not arbitrary.
Why 6.706 km
It is one twenty-fourth of 100 miles. Run one every hour for a day and you have covered 100 miles in 24 hours — the oldest benchmark in ultrarunning — with the arithmetic doing itself:
So a backyard's distances are legible at a glance in a way most ultras' are not. Twelve yards is a half-century, twenty-four is a hundred, forty-eight is two hundred. No one has to convert anything.
| Yards | Distance | In miles | Elapsed |
|---|---|---|---|
| 1 | 6.7 km | 4.2 miles | 1 hour |
| 6 | 40.2 km | 25.0 miles | 6 hours |
| 12 | 80.5 km | 50.0 miles | 12 hours |
| 24 | 160.9 km | 100.0 miles | 24 hours |
| 36 | 241.4 km | 150.0 miles | 36 hours |
| 48 | 321.9 km | 200.0 miles | 48 hours |
| 72 | 482.8 km | 300.0 miles | 72 hours |
| 100 | 670.6 km | 416.7 miles | 100 hours |
What it means for pace
An hourly cut-off over 6.706 km means the slowest lap that still counts is about 8:57 per kilometre (14:24 per mile) — a brisk walk. That sounds generous, and on lap one it is. The catch is that anything you spend approaching that limit you are not spending asleep.
Most people who go a long way settle somewhere between 45 and 52 minutes a lap, which is 6:43 to 7:45 per kilometre. The calculator will turn any lap time into the rest it earns.
Does every race use it?
Almost all do, because comparable results are the point — a satellite race's yard count only means something against everyone else's. Courses vary in surface and climb, and many races run a trail loop by day and a road loop at night, but the distance holds. Where a race deviates, it says so.
Backyard Ultra Live measures your loop from the GPX you import rather than assuming the standard figure, so a course that is 6.72 or 6.68 is read as what it actually is. See a worked example, or the format explained in full.