Selection guide
Arcade button sizes, panel cutouts and how to measure what you have.
Button size is the first thing that has to be right on a control panel, because it fixes the hole pattern. Everything else — colour, lamp voltage, switch rating — can change later without touching the panel. This guide covers the sizes in commercial use, the cutout each needs, and how to identify an unmarked button.
Arcade buttons are named by the diameter of the panel hole they drop into, not the diameter of the cap you press. The three sizes in commercial use are 24 mm, 28 mm and 30 mm. 30 mm is the standard action button across most cabinet layouts, 24 mm is used for start, coin and admin rows where buttons sit close together, and 28 mm appears on Japanese-pattern panels. A 30 mm button needs a 30 mm cutout and will not fit a 28 mm hole.
The three sizes and where each is used
30 mm is the default action-button size on the great majority of upright and cocktail cabinets. It gives a cap face large enough to hit reliably under fast play and leaves room for a full-size micro switch behind the panel. If you are replacing worn buttons on an existing machine and nothing is marked, 30 mm is the first size to test.
24 mm buttons are used where a row has to be compact: player start, coin insert, service and test functions, and secondary rows on fighting layouts. Because the bodies are narrower they can be spaced tighter without the flanges touching. 28 mm sits between the two and is most often seen on Japanese-pattern panels and on machines built to a Japanese cabinet standard.
Cutout diameter is not the same as cap diameter
The number in a button name is the panel cutout it requires. The visible cap is always wider than that, because the flange has to overlap the hole and hold the button against the panel. A 30 mm button typically presents a cap of roughly 33 to 36 mm depending on the body style, which is why measuring the cap of a button already in a panel gives the wrong answer.
To measure correctly, remove the button and measure the barrel — the threaded or snap-in cylinder that passes through the panel — not the face. If you cannot remove it, measure the hole from the underside of the panel.
Panel thickness decides the mounting type, not the size
Every size is available in more than one mounting style, and the style has to match panel thickness. Snap-in bodies grip with sprung tabs and are designed for thin panels, typically under about 3 mm; they install without tools but do not tolerate a thick or laminated panel. Screw-in bodies use a threaded barrel and a lock nut and cope with a wider thickness range because the nut simply travels further up the thread.
Mixing this up is the most common reason a correctly sized button will not seat: the cutout is right, but a snap-in body cannot reach past a 6 mm plywood panel to latch. Confirm both numbers — cutout diameter and panel thickness — before ordering.
Identifying an unmarked button on an existing machine
Pull one button out and note four things: barrel diameter in millimetres, mounting style (sprung tabs or a threaded barrel with a nut), whether a lamp is fitted, and the terminal type on the micro switch. Those four values are enough to specify a replacement, even with no model number anywhere on the part.
If the machine is being refreshed rather than repaired, this is also the moment to decide whether to stay with the original size. Changing size means re-drilling the panel, so it is worth doing during a rebuild and rarely worth doing as a repair.
| Size | Panel cutout | Typical use | Notes |
|---|---|---|---|
| 24 mm | 24 mm | Start, coin, service and admin rows | Tightest spacing; smaller cap face |
| 28 mm | 28 mm | Japanese-pattern control panels | Not interchangeable with 30 mm cutouts |
| 30 mm | 30 mm | Main action buttons on most cabinets | Most widely stocked size |
Frequently asked questions
Will a 30mm arcade button fit a 28mm hole?
No. The number is the panel cutout the body needs, so a 30 mm button requires a 30 mm hole. Fitting it into a 28 mm panel means enlarging the cutout with a step drill or hole saw.
What size are most arcade buttons?
30 mm is the standard size for main action buttons on most arcade cabinets. 24 mm is used for start and coin rows, and 28 mm appears mainly on Japanese-pattern panels.
How do I measure an arcade button I already have?
Measure the barrel that passes through the panel, not the cap you press. The cap is always wider than the cutout because the flange has to overlap the hole.
Can I mix button sizes on one control panel?
Yes, and most commercial layouts do: 30 mm for the action cluster and 24 mm for start, coin and service. Each size just needs its own cutout diameter.
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