MX Spacing vs Choc Spacing: What They Are, How to Differentiate & Choose for DIY Keyboards

When building or upgrading a mechanical keyboard, two terms often cause confusion: MX spacing and Choc spacing. These aren’t just about how close keys are placed—they directly determine which keycaps fit your switches. At the core of the difference is one critical feature: the stem design (the connector between keycaps and switches). Let’s break down what each spacing standard means, and which keycaps work with them.​

MX Spacing: The Universal Standard with Cross-Stem Keycaps​

MX spacing is the most common standard in mechanical keyboards, defined by two key traits: a consistent switch pitch and a universal stem design.​

  • Key Measurement: 19.05mm between the centers of adjacent switches. This spacing has become the industry norm, used in everything from full-size keyboards to compact 60% layouts.​
  • Stem Design: All MX-spaced setups use a cross-shaped stem (often called an “MX stem”). This universal design is why most aftermarket keycaps are labeled “MX-compatible”—they fit any switch with this stem.​
  • Compatible Switches:​
  • Traditional MX switches (Cherry MX, Gateron MX, Kailh Box MX).​
  • Low-profile variants like Kailh Choc V2 switches and Gateron Low-Profile switches (e.g., Kailh Choc V2, Gateron Low-Profile). These retain the cross stem and MX spacing, even with a shorter height.
Diagram of Cross Stem Partial Switches

MX spacing 19.05mm with cross-shaped stem, compatible with MX and low-profile switches

Choc Spacing: The Compact Alternative with Choc V1 Stems​

Choc spacing is a specialized standard for ultra-compact, low-profile keyboards. Unlike MX spacing, it’s tied to a unique stem design that limits keycap options.​

  • Key Measurement: 18mm between switch centers—narrower than MX spacing, allowing for tighter, more portable layouts (e.g., 40% keyboards).​
  • Stem Design: Choc spacing exclusively uses the Choc V1 stem (a proprietary rounded stem from Kailh). This stem is not cross-shaped, so it won’t work with MX-compatible keycaps.​
  • Compatible Switches: Only first-generation Kailh Choc V1 switches. These switches are designed specifically for Choc spacing and require matching Choc V1 keycaps.​

MX Spacing vs. Choc Spacing: At a Glance​

Feature​MX Spacing​Choc Spacing​
Switch Pitch​19.05mm​18mm​
Stem Shape​Cross-shaped (MX stem)​Rounded (Choc V1 stem)​
Keycap Compatibility​All MX-compatible keycapsOnly Choc V1 keycaps
Compatible Switches​MX switches, Kailh Choc V2 switches, Gateron Low-Profile switchesKailh Choc V1 switches only​

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How to Choose: MX or Choc Spacing?​

  • Choose MX spacing if: You want flexibility. With cross-stem keycaps, you can mix and match from thousands of options, including low-profile sets for Kailh Choc V2 switches or Gateron Low-Profile switches. It’s ideal for most users, from beginners to custom builders.​
  • Choose Choc spacing if: You prioritize compactness and don’t mind limited keycaps. This is best for niche builds where size is critical (e.g., travel keyboards) and you’re comfortable using Choc V1-exclusive parts.​

Pro tip: Always check your switch model! Choc V2 switches look similar to Choc V1, but they use MX spacing and cross stems—so they need MX-compatible keycaps, not Choc V1 ones.

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