Mechanical Keyboard Sizes Unlocked: 7 Crucial Checks to Avoid Buying Wrong Keycaps

Buying keycaps that don’t fit your keyboard is like ordering shoes for the wrong feet. Let’s decode keyboard layouts and keycap sizes with actionable checks.

1. Know Your Layout

Keyboard layouts aren’t just about key counts:

  • 100% (Full-size): Needs 104-108 keys, including numpad and full nav cluster.
  • TKL (Tenkeyless): 87 keys – no numpad but full modifiers.
  • 75%: Compact nav cluster (vertically aligned keys).
  • 65%: No function row, may have split right shift.
  • 60%: No arrows/numpad – check right shift size!
  • 40%: Extreme compact – custom keycaps often required.

2. Right Shift Trap

The silent killer of compatibility:

  • Standard: 2.75U (common on TKL/100%)
  • Compact: 1.75U (common on 65%/75% boards)
  • Split Shift: Some 60% boards use 1U right shift

3. Spacebar Sizing

Not all spacebars are 6.25U:

  • 6.25U: Standard for most boards
  • 7U: Common on high-end customs (e.g., TGR Alice)
  • Split Space: Some ergo boards use two 2.75U spaces

4. Bottom Row Warfare

The cursed zone where standards clash:

  • Standard ANSI: 1.25U x6 + 6.25U space
  • Compact (e.g., Razer): 1.5U-1U-1.5U + 6U space
  • Apple Layout: Command/Option keys differ

5. ISO vs ANSI

Regional layout differences:

  • ISO Enter: Tall "L-shaped" enter key (needs specific keycap)
  • ANSI Enter: Rectangular key (standard in US/Asia sets)
  • Key Legends: Nordic/UK ISO layouts need extra symbols

6. Specialty Keys

Niche layouts demand attention:

  • Alice Layout: B-staggered keys + split space
  • Ortholinear: Grid-style 1U keys (e.g., Planck)
  • Macro Pads: Often use 1U keys exclusively

7. Stabilizer Types

Stab compatibility affects keycap fit:

  • Costar: Wire-through design (needs cherry-style keycap stems)
  • Cherry: Clip-in stabilizers (most common)
  • Plate-Mounted: Requires keycaps with stab cutouts

Pre-Purchase Checklist

  1. Take keyboard layout photos (top/bottom rows)
  2. Measure right shift/spacebar in "U" units
  3. Verify ISO/ANSI enter shape
  4. Confirm stabilizer compatibility
  5. Check if set includes 1.75U shift/7U space
  6. Search "[Your Keyboard Model] + keycap size"
  7. Buy from vendors with size charts

Life-Saver Tools:

  • Keyboard Layout Editor (online visualizer)
  • "Keycap Dimension Checker" templates (printable PDF)
  • r/MechanicalKeyboards subreddit troubleshooting thread