Yardage is a sum, and the interesting part is what is not in it
Adding up the legs of a course walk is the easy half. Twelve legs of 40, 32, 36, 30, 44, 38, 30, 42, 36, 34, 40 and 48 feet come to 450 feet, which is 150 yards. Against a posted 45 seconds that is 3.333 yards a second, and that number is the one worth carrying around, because it is comparable between courses in a way that a raw time never is.
What the sum leaves out is the line. Legs measured obstacle to obstacle are straight, and nothing runs a course in straight lines with instantaneous corners. Every change of direction is an arc, and the radius of that arc is a choice.
The arc arithmetic, and why it is worse than it looks
A turn of angle A degrees taken at a radius r covers an arc of A/360 times 2 pi r. Take the same turn at r plus e and the extra distance is A/360 times 2 pi e — the original radius drops out entirely. That is the useful part: you do not need to know the tight radius to price the difference, only how much wider the line is.
For a 90 degree turn, the extra distance is pi/2 times the extra radius, or about 1.571 feet per foot of width. Three feet wide is 4.71 feet on that one turn. Eight of them is 37.7 feet, and 37.7 feet on a 450 foot course is 8.4 percent — at 3.333 yards a second, 3.77 seconds. On a course where the posted time is 45 seconds, close to four seconds has gone into ground nobody chose to cover.
| Extra radius | 90 deg turn | 135 deg turn | 180 deg turn | Eight 90 deg turns |
|---|---|---|---|---|
| 1 ft | 1.57 ft | 2.36 ft | 3.14 ft | 12.6 ft |
| 2 ft | 3.14 ft | 4.71 ft | 6.28 ft | 25.1 ft |
| 3 ft | 4.71 ft | 7.07 ft | 9.42 ft | 37.7 ft |
| 5 ft | 7.85 ft | 11.78 ft | 15.71 ft | 62.8 ft |
Wraps are where it hurts. A 180 degree turn costs twice what a 90 costs for the same extra radius, so a course with three tight wraps in it punishes a wide line roughly twice as hard as a course of open right-handers.
Rate, not time
Yards per second is worth more than a stopwatch reading because it survives being carried to a different course. A 45 second posted time on 150 yards and a 60 second posted time on 200 yards are the same rate — 3.333 yards a second — and knowing that lets you compare two things that otherwise look nothing alike. The table the calculator prints for posted times either side of the one you entered exists for the same reason: it shows how sensitive the rate is to the time, which on short courses is a lot.
Everything on this page is arithmetic on numbers you supplied. The posted course time comes from the score table on the day and from nowhere else, and no figure here is a statement about what any dog should do, can do, or ought to be asked to do.
Where this hands off
If you are laying the ring out rather than walking it, the agility ring size calculator goes the other way: obstacle count and spacing to a footprint, with the run-off band priced out. For pace arithmetic in its general form — solving any two of pace, time and distance, with splits — the running pace calculator and the speed and pace converter already do that job properly. If you are working out how many of these runs fit in a day, that is the trial ring schedule calculator.
Questions people ask
Should I measure the legs by pacing or with a wheel?
Whichever you will actually do consistently. A measuring wheel is the accurate option and a known stride length is the practical one. The thing that matters more than the method is using the same method every time, because the value of a yards-per-second figure is in comparing it with the last one, and a systematic error of five percent cancels out entirely in that comparison while a random one does not.
What counts as a turn going wide?
Whatever you decide to count. The field is there so you can price a specific idea — say, the four turns on a course where you know the line drifts — rather than have the page assume something. If you want the whole-course worst case, put in every change of direction. If you want the difference between two handling plans, run it twice with different turn counts and compare the totals.
Why does the extra radius not depend on how tight the turn already is?
Because the arc length formula is linear in the radius. Arc at radius r plus e minus arc at radius r is A/360 times 2 pi times e, and r cancels. It is one of the rare bits of geometry that is genuinely easier than people expect, and it means you can price a wider line without ever measuring the tight one.
Is the yards per second figure a target?
No. It is a description of two numbers you typed: the path you measured and the time somebody posted. It says nothing about any dog, any handler or any class, and no page should offer that. Questions about what any animal should be asked to do belong to a veterinarian and to your own judgement, not to arithmetic.
Can I use this for other course sports?
The arithmetic is generic — legs, a total, arcs on the turns, and a rate against a posted time. Anything run against the clock on a measured path fits it. What does not transfer is the interpretation, since every sport and every organization posts times on its own basis, so the input has to come from that sport rule book rather than from a figure carried over from somewhere else.