Dartboard Height, Throw Distance and the Diagonal That Squares Them
Steel-tip: centre of the bull 5 ft 8 in (1727 mm) above the finished floor, throw line 7 ft 9¼ in (2369 mm) back from the board face, and the bull-to-oche diagonal 9 ft 7⅜ in (2930 mm). Soft-tip keeps the same height but moves the throw to 8 ft (2438 mm), which pushes the diagonal to 2988 mm. Measure the diagonal last and treat it as the check digit on the other two.
By the Darts Fella Editorial Team
A steel-tip board hangs with the centre of the inner bull 5 ft 8 in (1.73 m) above the finished floor, and the throw line sits 7 ft 9¼ in (2.37 m) back from the face of the board. The number almost nobody prints is the third one: the diagonal from the centre of the bull down to the player's edge of the throw line should come out at 9 ft 7⅜ in (2.93 m).
That diagonal is the whole trick. It is the hypotenuse of the other two measurements, so if it lands where it should, the height and the throw are both right and you can stop fiddling. If it doesn't, one of them is wrong and you now know to go looking. Run the arithmetic on the published figures and they agree to within about a millimetre, which tells you the governing bodies didn't pick them at random.
Soft-tip is where people come unstuck. Same height, longer throw — 8 ft flat (2.44 m) — which puts the diagonal at 2.99 m rather than 2.93 m. Convert a steel setup to a machine, move only the tape on the floor, and you'll have a board that measures correctly on two axes and fails on the third.
Every configuration, in three unit systems
Five setups cover almost everything a player will actually be building, plus one convention that gets used constantly and is governed by nobody. The tolerance column is ours, not a rulebook's — the published rules give nominal figures with no plus-or-minus, and a tournament official measures to the printed number. What follows is what we'd accept on a wall before pulling the bracket off and starting again.
Configuration Bull height (floor to centre of inner bull) Throw distance (board face to throw line) Diagonal (bull to throw line) Build tolerance we'd accept Steel-tip, WDF and PDC senior 5 ft 8 in / 173.0 cm / 1727 mm 7 ft 9¼ in / 237.0 cm / 2369 mm 9 ft 7⅜ in / 293.0 cm / 2930 mm ±3 mm height, ±3 mm throw, ±5 mm diagonal Soft-tip electronic, standard machine league 5 ft 8 in / 173.0 cm / 1727 mm 8 ft 0 in / 243.8 cm / 2438 mm 9 ft 9⅝ in / 298.8 cm / 2988 mm ±3 mm height, ±3 mm throw, ±5 mm diagonal Youth and junior competition (governed events) 5 ft 8 in / 173.0 cm / 1727 mm 7 ft 9¼ in / 237.0 cm / 2369 mm 9 ft 7⅜ in / 293.0 cm / 2930 mm No separate junior geometry exists — full adult figures apply Under-12 home and club practice (convention only) 5 ft 0 in / 152.4 cm / 1524 mm 7 ft 0 in / 213.4 cm / 2134 mm 8 ft 7¼ in / 262.2 cm / 2622 mm ±5 mm; nothing in this row is governed by anybody Wheelchair play (WDF wheelchair rules) 4 ft 6 in / 137.2 cm / 1372 mm 7 ft 9¼ in / 237.0 cm / 2369 mm 8 ft 11¾ in / 273.7 cm / 2737 mm ±3 mm height, ±3 mm throw, ±5 mm diagonal Raised-oche pub variant, 38 mm oche, diagonal taken to its top back edge 5 ft 8 in / 173.0 cm / 1727 mm 7 ft 9¼ in / 237.0 cm / 2369 mm, from the back edge of the oche 9 ft 6½ in / 290.9 cm / 2909 mm ±3 mm; expect roughly 21 mm shorter than the floor-datum diagonal Set the height, set the throw, then measure the diagonal as a check digit. If the diagonal lands inside tolerance, both other measurements are right; if it doesn't, one of them isn't. That last row surprises people. Stand a 38 mm raised oche on the floor and measure the diagonal to its top back edge rather than to the floor, and you lose about 21 mm off 2930 mm, because you've shortened the vertical leg of the triangle without touching the horizontal one. Neither figure is wrong. They're answers to different questions, and a lot of arguments in pub back rooms are two people measuring to two different datums and both being correct.
The under-12 row is a convention, widely used and not written down anywhere binding. Junior competition under the recognised bodies uses adult geometry. If a child is playing in graded events, hang the board at 1727 mm and let them stand where they like in practice.
Where each measurement is actually taken from
Nearly every out-of-square board we hear about is a datum problem, not an arithmetic problem. The person measured the right distance from the wrong thing.
Measurement The correct datum Nominal (steel-tip) The mistake that costs you millimetres Bull height Finished floor to the centre of the inner bull — the 50, not the 25 ring 1727 mm Measuring to the geometric centre of the board's outer rim, or to the top of the 20 wedge. On a board with any mounting slop the two differ by several millimetres. Throw distance A plumb line dropped from the face of the board (the wire plane) to the player's edge of the throw line 2369 mm Measuring from the wall. A bristle board is 38-40 mm thick, so you'll be that much too long before you start. Diagonal Centre of the inner bull to the player's edge of the throw line, at floor level 2930 mm Running the tape to the front of a raised oche instead of the back edge, which is where the throw is defined. Raised oche Minimum 38 mm high, minimum 610 mm long, throw measured from its rear edge 38 mm × 610 mm Using a strip of tape as an oche in league play. Tape has no rear edge to stand behind and no height to feel. Floor datum The finished floor — on top of the carpet, mat or rubber tile, not the subfloor n/a Hanging the board to bare boards, then laying a 12 mm mat. Every measurement in the room is now 12 mm wrong. Board rotation The 20 segment centred vertically, on the same plumb line used for the throw 20 at top dead centre Rotating the board to spread wear and never re-checking that the 20 came back to vertical. Use this as a fault-finding list on any board that measures right on paper but plays wrong — the error is almost always in one of these six datums. Hanging order that stops you drilling twice
Do it in this sequence and you'll only make one set of holes.
- Put the floor covering down first. All of it. Every measurement below references the finished surface you'll be standing on.
- Mark a vertical plumb line on the wall at the board's centre. A weighted string beats a spirit level here — walls are rarely as plumb as they look.
- Measure 1727 mm up that line from the finished floor and mark it. That mark is where the centre of the inner bull is going, not where the bracket goes.
- Offer the board up dry, with the bracket loose, and set the 20 wedge on the plumb line. Fix the bracket only once the bull sits on the mark and the 20 is vertical.
- Drop the plumb line from the board face — the wire plane, not the wall — and mark the floor at that point.
- From the floor mark, run 2369 mm out and set the throw line. Steel-tip. For soft-tip, 2438 mm.
- Now run the diagonal from the bull to the player's edge of the throw line and read it against the table above. If it's outside ±5 mm, the height or the throw is out and you have not finished.
One thing worth doing while the board is still loose: check the wall is flat behind it. A board tilted forward at the top by even two or three degrees changes the effective height at the bull and throws the diagonal out, and it will also increase bounce-outs on the top of the board because the darts are arriving at a worse angle.
The board has its own published geometry
The setup numbers only matter because the target is a fixed size. Every regulation bristle board is built to the same ring dimensions, which is why a treble 20 is the same width of opportunity in a garage in Doncaster as it is anywhere else.
Feature Dimension Measured as Why it matters to your setup Playing surface diameter 451 mm (17¾ in) Outer edge of the double ring wire to outer edge, across the board Anything materially under 451 mm is a novelty board, not a regulation one Double ring, outer edge 340 mm diameter (170 mm radius) From the centre of the bull Sets the outer scoring limit — darts landing past this are worth nothing Double ring, inner edge 324 mm diameter (162 mm radius) From the centre of the bull Gives an 8 mm scoring band, which is the whole target on a double out Treble ring, outer edge 214 mm diameter (107 mm radius) From the centre of the bull The reason a treble 20 rewards vertical accuracy more than lateral Treble ring, inner edge 198 mm diameter (99 mm radius) From the centre of the bull Another 8 mm band — same width as the double, much smaller arc length Outer bull (25) 31.8 mm diameter From the centre of the bull Your reference point for the height measurement is inside this, not on it Inner bull (50) 12.7 mm diameter From the centre of the bull This is the datum for bull height and for the diagonal Segment count and width 20 segments, 18° each Around the full circle Wedge width grows with radius, which is why doubles punish sideways error less than trebles do Typical board thickness 38-40 mm Front face to back of the sisal The gap between the wall and the board face — subtract it or your throw distance is long Check a secondhand or unbranded board against the first two rows before you hang it; if the playing diameter or the double ring is off, no amount of careful measuring downstream will fix it. Boards wear from the inside out. The treble 20 bed goes first, then the treble 19, then the bull. Rotating the board redistributes that wear, and the standard rotation moves the board by one segment at a time — but every rotation is another chance to leave the 20 off vertical, so re-plumb it each time rather than eyeballing it.
Rooms that fight back
Most homes have one obstacle that the regulation figures ignore, and the honest answer is usually to move the board rather than bend the numbers.
Low ceilings are the common one. At 1727 mm to the bull, the top of the board sits around 1953 mm off the floor, so a 2.1 m ceiling is tight but workable and anything under about 2.0 m starts to interfere with the throw arc on a lobbed release. Sloping ceilings under stairs are worse than low flat ones, because the slope is usually over the throwing position rather than over the board.
Skirting boards and baseboards push the board forward at the bottom if the bracket sits low enough to catch them, tilting the face. Check the board hangs plumb with a spirit level held vertically against the face, not against the wall.
Then there's the floor. Carpet compresses under a standing player by three or four millimetres, hard tile doesn't compress at all, and a rubber dart mat adds anywhere from 3 mm to 12 mm depending on the product. Hang to the surface you'll actually stand on and the problem disappears.
Run-back, side clearance and the throwing lane
Nothing here is governed for home installs. These are the clearances that stop a room from being annoying to play in.
- Behind the throw line: 600 mm minimum, 900 mm comfortable. You need room to step back and look at the board between throws, and room for a second player to stand without being clipped.
- Either side of the board centre line: 900 mm minimum, 1200 mm comfortable. Stray darts bounce sideways more often than people expect, and a wall close to the board on one side changes how you address it.
- Above the board: 300 mm minimum to the ceiling. Below that, high darts strike the ceiling on the way in.
- Board to the nearest internal corner: 1000 mm. Corners funnel bounce-outs back at your feet.
- Lane width overall: 1500 mm is playable, 2000 mm is pleasant. Any narrower and you'll find yourself squaring up to the board differently at home than you do in a league venue, which quietly costs you.
- Floor in front of the board: keep the first 500 mm clear of anything a dart can land point-first into and be damaged by. A dropped mat pays for itself in points.
Checking a board someone else hung
Take a 5 m tape and four minutes. Start at the diagonal, because it's one measurement that tests two.
Hook the tape on the throw line at the player's edge, run it to the centre of the bull, and read it. Steel-tip should give 2930 mm. If it's long, either the board is too high or the throw is too far back. If it's short, the reverse. From there, measure the height on its own, and whichever of the two is wrong will be obvious.
One recurring finding in pubs: the board is correct and the oche has drifted. Brass oche strips get kicked, tape peels and gets re-stuck a centimetre out, and a raised wooden oche gets nudged when the floor is mopped. Rooms that are checked once a year are usually fine on the wall and wrong on the floor.
Second recurring finding: the board was hung to the correct height and then a new surround was fitted, and the surround's lip has pushed the board out from the wall by 15 mm without anyone re-measuring the throw. Any change to what's behind the board is a change to the throw distance.