The Dressage Arena: Dimensions, Letters and Geometry

The standard dressage arena is a flat, level rectangle 20 metres wide and 60 metres long, marked by twelve letters around its low perimeter fence — A, K, V, E, S, H, C, M, R, B, P, F, read clockwise — with five more (D, L, X, I, G) understood along the unmarked centre line. A smaller 20 × 40 metre arena with eight perimeter letters serves the introductory levels. Every dressage test ever written is a sequence of instructions between these letters, and — the sport’s favourite piece of trivia — nobody knows for certain why these particular letters were chosen. To-scale diagrams of both arenas, with every letter and measurement, are collected in the printable arena diagrams.

Two arenas: 20 × 60 and 20 × 40

The standard arena is compulsory for every FEI-level test, from the young rider divisions to the Grand Prix and the Olympic Games. The national systems commonly publish their lowest tests in short-arena versions or permit either size, and the small arena remains standard at grassroots and unaffiliated level, not least because many private schooling arenas are built to 20 × 40. The two are geometrically related — the small arena is the standard one with the middle 20 metres removed — which is why the letter sequence of the small arena survives intact inside the large one.

The letters in order

In the standard arena, A stands at the midpoint of one short side (the entrance end) and C at the midpoint of the other, where the presiding judge sits. E and B face each other at the midpoints of the long sides. K and F flank the A end, H and M the C end, and V, S, P and R fill the gaps between them. Read clockwise from the entrance, the perimeter runs:

A – K – V – E – S – H – C – M – R – B – P – F

Down the centre line, five further points are defined but never physically marked, since a marker would stand in the horses’ path: D (level with K and F), L (level with V and P), X (the exact centre, level with E and B), I (level with S and R) and G (level with H and M). The full centre line therefore reads A – D – L – X – I – G – C.

The small arena drops V, S, R and P from the perimeter and L and I from the centre line: clockwise A – K – E – H – C – M – B – F, with D – X – G down the middle.

Because the sequence is arbitrary, riders learn it by mnemonic. The classic, fitting the small arena, is “All King Edward’s Horses Can Make Big Fences” (with “Can Manage Big Fences” and ruder variants in wide circulation). The twelve-letter arena needs a longer sentence, and no single version has won out; one circulating example is “All King Victor’s Elegant Show Horses Can Make Really Beautiful Prancing Figures”. None is official — the mnemonics are folk pedagogy, invented and reinvented at riding schools everywhere.

The measurements

The letters are not evenly spaced. The corner letters stand 6 metres from their corners; the remaining long-side letters divide the rest at 12-metre intervals in the standard arena and 14-metre intervals in the small one. Measured from the A short side:

A and C sit at the midpoints of their short sides, 10 metres from each corner. The physical letter markers stand just outside the fence, so the named point is on the track itself. Setting an arena out accurately is its own small craft — the practical check is that the two diagonals of a true 20 × 60 rectangle measure equal at about 63.25 metres — and the arena diagrams include the full measurement tables for both sizes.

The unknown origin of the letters

Why A, K, V, E, S, H and the rest? The honest answer is that no one knows. The lettered arena appears in international sport around the 1920 Olympic Games without any recorded explanation, and no primary document naming the letters’ origin has ever been produced.

The most widely repeated theory points to the stable yard of the Imperial German court in Berlin before 1918. The yard — by the usual account roughly 20 by 60 metres — is said to have had letters painted on its walls marking where each rider’s horse was held to await mounting, and a tidy list of courtier ranks circulates to match: K for Kaiser, F for Fürst (prince), P for Pferdknecht (groom), V for Vassal, E for Edeling or Ehrengast (guest of honour), B for Bannerträger (standard bearer), S for Schatzkanzler (chancellor of the exchequer), R for Ritter (knight), M for Meier (steward) and H for Hofmarschall. The story is appealing and may contain truth, but it is reported, not documented: no contemporary source confirms the assignments, and the theory does not explain C or the centre-line letters at all.

A second theory credits the German cavalry, whose riding schools of the late nineteenth century used lettered walls for schooling commands; an 1882 cavalry manual shows a 20 × 40 metre school marked with letters, though not the modern set. A third suggestion — that the letters abbreviate cities of the Roman Empire — circulates with even less behind it. The responsible summary is that the letters are conventions, not abbreviations: they stand for nothing except the points they mark, and “what do the letters stand for” is a question the sport has never been able to answer about itself.

The geometry riders actually use

The letters are only the visible part of the arena’s grid. Riders navigate by a set of derived lines and points that no marker shows.

The centre line and quarter lines. The centre line, A to C, is the test’s spine: every test begins on it, and straightness on it is judged head-on from C. The quarter lines run parallel to it, 5 metres in from each long side, and the middle levels use them for work off the supporting rail.

The circle points. The workhorse figure of the lower levels, the 20-metre circle, touches the track at points the letters only approximate. A 20-metre circle at A or C touches each long side 10 metres from the short side — 4 metres beyond the corner letters — and crosses the centre line 2 metres beyond L or I respectively. A 20-metre circle at E or B is centred on X, touches both long-side midpoints, and reaches 10 metres either side of X along the centre line. Only in the small arena does the geometry come out round: there, a 20-metre circle at A or C passes exactly through X. Learning these unmarked tangent points is the first exercise in arena geometry, because a circle ridden letter-to-letter by guesswork becomes an egg — an accuracy fault any judge can measure, as the article on common faults sets out.

The corners. The corners belong to the track but not to the figures: a circle or diagonal never enters them. A correctly ridden corner is a quarter of a small circle, and its depth scales with the horse’s schooling — conventionally the arc of a circle of roughly 10 metres for a novice horse, tightening towards 6 metres in collected work. Deep corners buy time and balance to prepare what follows; cut corners give both away.

Riding “at” a letter. Movements are prescribed and judged from letter to letter — “H–X–F, change rein, medium trot” — and the convention is that a transition happens as the rider’s body passes the letter, not the horse’s nose. Since judging of a movement begins and ends at its markers, placement is not cosmetic: a half-pass started three strides after the letter is a half-pass partly unshown, and a transition drifting past its marker is marked as late.

The judges around the arena

The letters also seat the officials. The presiding judge sits at C, 3 to 5 metres behind the short side, looking straight down the centre line; national classes are often judged from C alone. International panels of five sit at C, E, B, M and H — the M and H judges along the short side either side of C — and championships and the Olympic Games use seven, adding K and F near the A end. Each seat sees a genuinely different test: straightness from C, the profile of a half-pass from B or E. How the panel’s views become one percentage is the subject of judging and scoring.

Construction: footing, boards and the entrance

Competition arenas are specified with the same precision as the letters. The surface must be flat and level; modern competition footing is typically a prepared sand mixture, often fibre-stabilised, replacing the grass arenas on which the sport was ridden for much of the twentieth century. The perimeter is a low white fence — under FEI rules about 30 centimetres high — designed to define the space without confining the horse; a horse leaving the arena with all four feet during a test is eliminated.

The entrance is at A. Under FEI rules it must be at least 2 metres wide and is closed once the combination has entered, opening again only after the final salute; at national shows the boards at A are commonly just left apart, with the gap serving as a permanent entrance. Around international arenas, a clear separation is kept between the fence and spectators, and the judges’ boxes are raised so that each panel member looks across, rather than along, the arena floor.

The letters on the test sheet

The arena’s grid is what makes a written test possible. Every line of a test sheet is an instruction anchored to letters — “A, enter collected trot; X, halt, salute”; “K–X–M, change rein, extended trot” — and every mark on the sheet is bounded by them, which is why the sheet can be read as a map of the ride. How the movement descriptions, directives and marks fit together is covered in reading a score sheet. Even the freestyle, which frees riders from prescribed lines, is choreographed and judged against the same lettered floor plan: the letters are the one part of a dressage test that never changes.

Sources

• Fédération Équestre Internationale — FEI Dressage Rules, 26th edition (updates effective 1 January 2026), 2026. https://inside.fei.org/fei/disc/dressage/rules
• Fédération Équestre Internationale — Dressage Rules full text (arena specifications), 2022 revision annex. https://inside.fei.org/system/files/16.2_GA%202022_Annex%2016.2_DRESSAGE%20FULL%20RULES_0.pdf
• United States Dressage Federation — Appendix F: Arena Set-Up, undated. https://www.usdf.org/EduDocs/Facility-Management/How_to_Set-Up_a_Dressage_Arena.pdf
• Eurodressage — The Story behind the Dressage Letters: Two Possible Explanations, 2005. https://eurodressage.com/2005/01/23/story-behind-dressage-letters-two-possible-explanations
• Equine World UK — Dressage arena layout and letters, undated. https://equineworld.co.uk/equestrian-sports/dressage/dressage-arena-letters-layout