What size is a dartboard?

Apr 23, 202311 min read

A regulation steel-tip dartboard is 451mm across overall, which is 17.75 inches and often rounded to 18 inches in product listings. The scoring area is smaller: the outside edge of the double ring to the opposite outside edge is 340mm.

Last reviewed: 24 August 2026. This guide explains dartboard diameter, scoring-area size, bull measurements, double and treble ring width, and the setup measurements that matter once the board is on the wall.

Regulation dartboard size infographic showing overall diameter, scoring area, ring width and bull measurements — The headline size is 451mm overall, but the playable scoring diameter is 340mm across the double ring.

The direct answer

A standard steel-tip dartboard is 451mm in overall diameter. In imperial measurements, that is 17.75 inches. Retailers often round this to 18 inches, which is why “18-inch dartboard” usually means a normal regulation-size board.

The actual scoring area is smaller than the board's full outside diameter. The important scoring measurement is 340mm from the outside edge of the double wire to the outside edge of the opposite double wire. The rest is outer board area, number ring area and construction.

Regulation dartboard dimensions

Measurement	Regulation figure	Why it matters
Overall board diameter	451mm / 17.75in	Headline board size
Scoring diameter	340mm	Outside double to outside double
Double and treble ring width	8mm	Multiplier target size
Inner bull diameter	12.7mm	50-point bullseye
Outer bull diameter	31.8mm	25-point outer bull
Bull height from floor	1.73m	Correct mounting height

Why listings say 18 inches

Most buyers think in simple product sizes, so many listings describe a standard board as 18 inches. That is a rounded figure. The more precise regulation diameter is 17.75 inches, or 451mm.

This is not usually a problem. If a recognised steel-tip bristle board is listed as 18 inches, it is normally describing the standard regulation board size. The issue is when sellers use vague “official size” wording without clear material, wire or measurement details.

Overall size versus scoring size

The biggest confusion is overall diameter versus scoring diameter. The board may be 451mm across, but the scoring area across the doubles is 340mm. Those are different measurements. The extra width includes non-scoring construction and the area outside the double ring.

For play, the scoring layout matters more than the outer edge. A player wins or loses based on the single, double, treble and bull areas, not the full circle of the board.

Double and treble ring size

The double and treble rings are narrow because they are meant to reward accuracy. The inside measurement is commonly given as 8mm. That is why a treble 20 looks large in theory but feels demanding in practice. The target is a thin band inside one segment.

This narrowness is also why wire quality matters. A thicker wire or older staple system can reduce the effective target area and increase bounce-outs. A modern thin-wire board can feel more forgiving without changing the regulation dimensions.

Bullseye measurements

The inner bull is 12.7mm across. The outer bull is 31.8mm across. The inner bull scores 50 and normally counts as a double for double-out rules. The outer bull scores 25.

These numbers explain why bull finishes are difficult. The centre target is small, and misses can land in the 25, single segments or outside the intended line. A bull finish is not only a mental pressure shot; it is physically a small target.

Height and distance still matter

Board size is only one part of a regulation setup. The bullseye should be 1.73m from the floor, and the oche should be 2.37m from the face of the board for steel-tip play. Measure from the board face, not from the wall.

This matters with cabinets and stands because the board projects forward. If you measure from the wall behind the board, the oche can end up too close. A regulation-size board mounted at the wrong distance is still an incorrect setup.

How to check your board at home

You do not need specialist tools to check the basics. Use a tape measure across the widest point of the board to confirm the overall diameter is around 451mm. Then check the scoring area by measuring across the doubles, from the outside edge of one double ring to the outside edge of the opposite double ring.

Do not worry if a home tape measure is a millimetre or two out because wires, angle and tape position can introduce small errors. What you are looking for is whether the board is clearly a standard steel-tip size or something smaller, toy-like or non-regulation.

Cabinets and surrounds do not change board size

A cabinet can make the whole setup look much larger, but it does not change the dartboard's scoring dimensions. The same is true of a surround. These accessories protect the wall, frame the board or add scorekeeping space, but the regulation measurements still come from the board itself.

This matters when planning a room. The board may be 451mm wide, but the cabinet doors, surround and safe miss area can require far more wall space. Measure the whole installation, not only the board diameter.

Using a stand with a regulation board

A dartboard stand can hold a regulation-size board, but the measurements still need checking. Set the bull to 1.73m, then measure the oche from the board face. Because the board sits forward on the stand, measuring from the wall or back legs will give the wrong throw distance.

Also check that the stand is stable enough for a full-size board. A standard bristle board has weight, and a weak stand can wobble. Size correctness does not help if the board moves every time a dart lands.

Soft-tip boards can differ

Electronic and soft-tip boards can use different sizes and distances depending on the format and machine. Many soft-tip setups use an 8-foot throw distance rather than the standard steel-tip 2.37m. If you are buying for soft-tip play, check the machine or league rules rather than assuming steel-tip measurements apply.

This article is mainly about standard steel-tip bristle dartboards. That is the board most players mean when asking “what size is a dartboard?”

Junior and novelty boards

Junior, magnetic, paper-wound and novelty boards can use different sizes. Some are designed for safety or casual family play rather than regulation practice. That is fine if everyone understands the purpose, but it is not ideal preparation for league or matchplay darts.

If a child is learning steel-tip darts under supervision, a regulation-size board at an appropriate safe setup may be better long term than a small novelty board. If safety is the priority, use the safer product, but do not confuse it with regulation practice.

What to check before buying

Check that the board is a proper bristle or sisal steel-tip dartboard, not a toy, paper-wound or magnetic board. Check the listed diameter, wire style, number ring and whether the board can be rotated. Size alone does not prove quality.

If you are buying for serious practice, choose a recognised board with thin wiring and clear segment definition. A board can be the right size and still be poor value if it wears quickly or causes frequent bounce-outs.

What “official size” should mean

A good product listing should make the size clear enough that you know it is a regulation steel-tip board. Ideally, it will state 451mm, 17.75 inches or a standard 18-inch rounded listing size. It should also say whether the board is bristle or sisal and whether the number ring can rotate.

Be cautious if “official size” is the only serious specification. A listing can use official-sounding language while hiding weak materials, thick wires or a fixed ring. For a practice board, dimensions and construction both matter.

Room planning

Before buying, measure the room, not just the wall. You need board height, throw distance, safe space behind the player and enough width for missed darts. A regulation board may fit on the wall, but the throw line may land in a doorway, walkway or furniture path.

For home practice, plan the whole lane. The board, surround, lighting, oche and player stance should all work together. If the room is too short, a regulation-size board will not fix the setup problem.

Replacement and rotation checks

When replacing a board, keep the bracket, cabinet and surround in mind. Most standard boards are designed around the same regulation diameter, but mounting hardware can differ. Check compatibility before assuming the new board will sit exactly like the old one.

Rotation also matters. A movable number ring lets you rotate the board body while keeping 20 at the top. This extends board life without changing the regulation size or scoring layout.

Why exact dimensions matter for improvement

If you practise on a non-standard board, your throw feedback becomes less transferable. A smaller board makes targets artificially hard; a larger or toy-style board makes them artificially easy. Neither gives the same feedback as the board you will meet in proper play.

Regulation size helps make practice honest. When you hit treble 20, miss into 1 or clip the wire, the result means something. That is the point of using the correct board and correct setup together.

Equipment and setup

Start with a proper dartboard. If wall mounting is not possible, use dartboard stands. Add dartboard surrounds to protect the area around the scoring surface.

Use consistent darts or complete dart sets, and keep spare flights, stems and points available. Board size gives the standard; equipment consistency gives the practice value.

Common mistakes

Thinking 18 inches is different from regulation: it is usually a rounded listing description.
Confusing board diameter with scoring diameter: 451mm and 340mm refer to different things.
Measuring the oche from the wall: measure from the board face.
Ignoring soft-tip differences: electronic boards may use different rules.
Buying by size only: material, wire and durability also matter.

Visual guide: how to apply this at the board

A practical decision map for applying the what size is a dartboard answer at a real board.

Use this matrix to turn the what size is a dartboard question into the right practice, scoring or setup decision.

Sources used

Bottom line

A regulation steel-tip dartboard is 451mm, or 17.75 inches, across overall. Listings often round that to 18 inches. The scoring area is 340mm across the doubles, the double and treble rings are about 8mm wide, and the bullseye must be mounted 1.73m from the floor for a correct steel-tip setup.