Keycap Row Codes and Profile Heights: What Is Documented

Cherry and OEM are the two profiles almost every mechanical keyboard ships with, and they are close enough that a lot of buyers treat them as interchangeable. They are not, but the differences are narrower and stranger than most comparison charts suggest, and the numbers those charts quote are on much shakier ground than they look.

What each name actually refers to

OEM profile, also called “standard profile”, is the shape used by the overwhelming majority of vintage and modern mechanical keyboards. It is not owned by one manufacturer. The same sculpting appears across different keycap mounts and different switch families, including Cherry MX, the Alps SKCL and SKCM series, and Mitsumi miniature mechanical switches. Boards built by Costar, including the Filco Majestouch and WASD Keyboards, plus Das Keyboard III, iOne, SteelSeries and Chicony, all use it. So do a number of rubber dome boards that happen to use a standard mount with separate sliders over each dome.

Cherry profile is narrower in origin: it is the profile Cherry uses on Cherry’s own keyboards. When Deskthority illustrates the difference between the two, the photograph it uses is of bottom row keycaps, which is a useful hint about where the divergence concentrates.

Both are sculptured and both are cylindrical on top. Sculpturing means each row gets its own shape: the top of the keycap sits at a different angle to its base, and that angle changes from row to row so the key tops curve toward the fingers. Cylindrical means the top surface scoops from side to side only, rather than in both directions the way a spherical profile does.

The honest answer about heights

Every profile comparison chart online carries a table of millimetre heights per row. Very few of them cite anything.

Neither Cherry nor the various owners of OEM-profile moulds publish a row-by-row millimetre table. That absence is why the circulating figures disagree with each other, and why two charts can put the same profile 1 mm apart without either being obviously wrong. What exists in public documentation is measurement by enthusiasts and the occasional figure published by a keycap manufacturer about its own family.

There is one clean anchor. Signature Plastics’ DSA family is documented at 0.291 inches, which is 7.39 mm, on every row, and that height is recorded as the same height as the home row of the OEM profile. So OEM’s home row is a known quantity, and everything else in an OEM height table is inferred from it.

The direction of the Cherry-versus-OEM difference is not in dispute: vendor descriptions and owner reports agree that Cherry sits slightly lower than OEM overall, and that the gap is most visible at the front of the board. Where charts diverge is the magnitude, and the reason is almost always the measurement point rather than a bad ruler. A figure for the tallest row and a figure for the home row of the same profile are both honest and several millimetres apart, which is exactly the trap in this section: the 7.39 mm above is a home-row number.

Set-level figures — the tallest point of the tallest row, the basis for the widely published 11.9 mm for OEM and 9.4 mm for Cherry — are collected, with their source and their measurement point stated, in the keycap profile height chart on our sister site Keycap Compare. Those two sets of numbers do not contradict each other; they answer different questions. Use either to rank profiles against one another, and neither to predict a caliper reading on a set that has not arrived.

	Cherry profile	OEM profile
Sculpting	Sculptured, per-row angle	Sculptured, per-row angle
Top surface	Cylindrical	Cylindrical
Origin	Cherry’s own keyboards	Industry-wide, many manufacturers
Overall height	Lower of the two	Taller; home row documented at 7.39 mm
Where they visibly differ	Bottom row sculpting	Bottom row sculpting
Rows interchangeable	No	No
Documented mm table published by vendor	No	No
Availability in aftermarket sets	Very wide	Very wide
Typical stock on prebuilt boards	Cherry boards	Most other brands

The row numbering trap

If you buy individual keycaps rather than a full set, row numbering will bite you eventually, because vendors do not agree on what to call a row. Most boards have four row profiles for the alphanumeric rows, with the function row and the space bar row borrowing their shapes from adjacent rows. The space bar itself is often taller and convex.

ISO/IEC 9995-1 labels rows alphabetically starting from the space bar row as row A, with the bottom alphabetic row as B and so on upward. Rows above the alphanumeric block start at K, and rows below the space bar count backwards from Z. Several manufacturers use this scheme, or mostly use it. Many do not.

Row	Signature Plastics	QWERKeys	WASD	Cherry	Leopold	Topre	KAT	MDA
Function row	1 (DCS uses 5)	1	4	E	E	E	5	1 or 0
Number row	1	1	4	E	E	E	4	1
Tab row (QWER)	2	2	3	D	D	D	3	2
Home row (ASDF)	3	3	2	C	C	C	2	3
Bottom row (ZXCV)	4	4	1	B	B	B	1	4
Space bar row	3 or 4	4	1	B	B	B	1	4 (convex 5)

Read that table before ordering a replacement key. Signature Plastics counts downward from the top, WASD counts upward from the bottom, and KAT inverts Signature Plastics entirely. An “R1” cap from one vendor and an “R1” cap from another can be opposite ends of the board.

DCS, the profile that complicates the comparison

Signature Plastics’ DCS family is worth knowing about, because a great many enthusiast sets are DCS rather than Cherry. Deskthority records its height profile as Cherry, so it is not a third height sitting between the two; it is documented as mostly profile-compatible with Cherry’s keys, but not exactly.

DCS stands for DIN standard height, cylindrical touch area, sculptured profile. It is documented as quite similar to Cherry profile in size and slant, with one specific exception: it differs significantly in the slant of the bottom rows. The detail matters if you mix parts. DCS’s bottom-two-row profile is angled more than Cherry’s row B while sitting lower than Cherry’s deprecated row A, which is exactly why an SP adapter kit and Cherry keys on the same row can come out inconsistent. Given that the bottom row is also where Cherry and OEM diverge, a DCS set is neither a Cherry clone nor an OEM clone at the front of the board.

Two DCS properties matter more than the sculpting for anyone chasing a particular sound.

DCS is documented as having thin walls, rounded corners and a coarse surface. Thin walls push the sound of a keypress higher and hollower, which is the opposite of what most buyers of thick PBT sets are looking for.

DCS keys also lack struts inside the cap around the key stem, and that means down-stroke noise cannot be damped with O-rings or silencing clips. If your plan for a noisy board is to fit O-rings, DCS removes that option before you start.

DCS is predominantly double-shot moulded ABS, with a clear polycarbonate run and unprinted PBT singles also documented.

Which one to buy

Choose OEM when you want the taller, more pronounced sculpting most people are already used to from a stock board, and when you want the widest possible aftermarket selection. It is the default for a reason.

Choose Cherry when you want the board to sit lower under the hands, when your case has a tight lip and clearance is a concern, or when you already like how a Cherry-branded board feels.

Choose a uniform profile such as DSA instead of either when you intend to rearrange the layout, since sculptured caps cannot be swapped between rows without making the profile uneven, which is the classic problem for anyone moving to Dvorak or a similar alternative layout.

One thing neither profile changes is whether the caps fit. Both are cut for the MX cross mount, and Cherry’s keycap specification puts that slot at 4.1 mm across the cross with arms 1.17 mm wide. That is a mount question, not a profile question, and it is covered in keycap wobble: causes, diagnosis and fixes.

Next steps

Profile choice only pays off if the set physically covers your board, and that is a width problem rather than a height problem. Work through keycap sizes explained before committing to a set, because the bottom row and the space bar are where profile-perfect purchases still fail.

The keycap profile and wall thickness sizer puts profile height, plastic and wall thickness, and switch LED orientation into one panel, including the row-code decoder from the table above.

For the wider picture of how profile, plastic and stem interact, start with keycap profiles, plastics and stem fit.