Written by Elizabeth · Published June 7, 2023
Reviewed & Updated by Olivia · Updated on July 28, 2026
Buying a replacement spacebar only works if you get the size right. Spacebars are measured in units (U), and the size you need depends entirely on your keyboard’s bottom row. Here is the full size chart, the stabilizer spacing for each, and how to measure what you already have.
⚡ Quick Answer
One keyboard unit (1U) is 19.05 mm. The most common spacebar is 6.25U, about 119 mm wide, used on standard ANSI keyboards, with stabilizers mounted 100 mm apart. The other common sizes are 7U (about 133 mm) and 6U (about 114 mm). Measure your existing spacebar and divide by 19.05 to find its size in units before ordering a replacement.
Spacebar Size Chart
Widths below are the layout footprint (units × 19.05 mm). The physical keycap is a fraction smaller so keys do not touch. Stabilizer spacing is the full centre-to-centre distance between the two stabilizer stems.
| Size | Width | Stabilizer spacing | Where you find it |
|---|---|---|---|
| 6.25U | 119.1 mm | 100 mm | Standard ANSI, most keyboards |
| 7U | 133.4 mm | 114.3 mm | Older and some custom bottom rows |
| 6U | 114.3 mm | 95.25 mm | Some 60% boards, vintage layouts |
| 4U | 76.2 mm | 50 mm | Compact and 40% layouts |
| 3U | 57.2 mm | Usually none | Split spacebar layouts |
| 2.75U | 52.4 mm | None | Split spacebar layouts |
| 2.25U | 42.9 mm | None | Split spacebar layouts |
📌 The quick rule. Width in millimetres ÷ 19.05 = size in units. A spacebar measuring about 119 mm is 6.25U; about 133 mm is 7U.
The Three Sizes That Matter Most
6.25U, the standard
This is what the vast majority of keyboards use. The bottom row runs 1.25U modifiers on either side of the spacebar (Ctrl, Win, Alt on the left; Alt, Fn, Menu, Ctrl on the right). Replacement 6.25U spacebars are the easiest to find in any keycap set, colour, or material.
- Width: 119.1 mm (6.25 × 19.05)
- Stabilizers: 100 mm apart, 50 mm either side of centre
- Bottom row: 1.25-1.25-1.25-6.25-1.25-1.25-1.25-1.25
7U, the wider option
A 7U spacebar sits in a bottom row with wider 1.5U modifiers. It was common on older boards and still appears on some customs. Keycap sets support it less often, so check the set includes a 7U spacebar before you buy.
- Width: 133.4 mm (7 × 19.05)
- Stabilizers: 114.3 mm apart, 57.15 mm either side of centre
- Bottom row: 1.5-1-1.5-7-1.5-1-1.5
6U, the awkward one
Found on some 60% boards and older keyboards. This is the size that catches people out, because a 6U bottom row shifts the modifier positions and very few keycap sets include the right kit. If your board is 6U, check keycap compatibility carefully before buying a set.
- Width: 114.3 mm (6 × 19.05)
- Stabilizers: 95.25 mm apart, 47.625 mm either side of centre
How to Measure Your Spacebar
You need a ruler or calipers and a keycap puller. It takes two minutes.
- Photograph the bottom row before you remove anything, so you can put the modifiers back correctly.
- Pull the spacebar with a wire keycap puller, lifting evenly from both ends so you do not bend the stabilizer wire.
- Measure the width edge to edge with the spacebar face down. Calipers are more accurate, but a ruler gets you close enough.
- Divide by 19.05 to convert to units. Round to the nearest standard size in the chart above.
- Check the stabilizer stems underneath. Measure centre to centre between them and compare against the chart to confirm.
💡 Faster shortcut. Count the modifier keys instead. If the keys either side of your spacebar are all the same small width (1.25U), you have a 6.25U spacebar. If some are noticeably wider, you are likely looking at a 7U bottom row.
Stabilizers: Cherry vs Costar
Size is only half the compatibility question. The other half is the stabilizer type your spacebar is designed for.
- Cherry style uses plastic stems that push into sockets on the underside of the spacebar. This is what almost every modern keyboard and keycap set uses.
- Costar style uses metal wire that clips into hooks moulded into the spacebar. Found on some older and prebuilt boards. Costar spacebars and Cherry spacebars are not interchangeable.
Turn your spacebar over: sockets mean Cherry, wire hooks mean Costar. Most replacement spacebars you buy today are Cherry compatible.
Installing a Spacebar Properly
- Lube the stabilizers first. This is much easier with the spacebar off and makes the single biggest difference to how it sounds. See our stabilizer lubing guide.
- Line up the stabilizer stems with the sockets on the spacebar before pressing anything.
- Press down evenly at both ends and the centre. Pressing one end first is what bends wires and pops stabilizers loose.
- Test it. Press the spacebar at the far left, far right, and centre. It should feel the same everywhere with no rattle or binding.
Common Spacebar Problems and Fixes
| Problem | Usual cause | Fix |
|---|---|---|
| Rattling | Dry or loose stabilizer wire | Lube the wire ends with dielectric grease; try the band-aid mod |
| Sticking or binding | Misaligned stems or wrong size | Reseat the spacebar; confirm the size matches your bottom row |
| One end feels dead | Stabilizer wire popped out | Remove the spacebar and reseat the wire in the housing |
| Hollow, echoey sound | Empty space inside the keycap and case | Add a little foam or a tape mod inside the spacebar |
| Sits crooked | Warped keycap or uneven stabilizers | Check it sits flat on a table; replace if warped |
Where to Buy a Replacement
Most keycap makers sell spacebars individually or as part of a set. What differs is the profile, material, and which sizes they include.
- GMK, thick ABS in Cherry profile, 6.25U and 7U. Premium colourways, premium prices.
- Signature Plastics, SA, DSA, and DCS profiles in 6.25U and 7U. The go-to for tall, spherical keycaps.
- Tai-Hao, budget-friendly ABS and PBT, mostly 6.25U, in a wide range of colours.
- EnjoyPBT, durable dye-sublimated PBT in Cherry and OEM profiles, 6.25U and 7U.
- Varmilo, dye-sublimated PBT in OEM profile, generally 6.25U.
- Keyreative, newer profiles like KAM and KAT in multiple sizes.
Whichever you pick, match the profile to your existing keycaps as well as the size. A Cherry-profile spacebar next to OEM-profile keys will sit at a slightly different height. Our keycap profile guide explains the differences, and the ABS vs PBT guide covers materials.
Frequently Asked Questions
What size is a standard spacebar?
The standard spacebar is 6.25U, which is about 119 mm wide (6.25 × 19.05 mm). It is used on most ANSI keyboards, with stabilizers mounted 100 mm apart. Other common sizes are 7U (133 mm) and 6U (114 mm).
How many mm is 1U on a keyboard?
One unit (1U) is 19.05 mm, which is 0.75 inches. That is the key pitch, or the spacing from the centre of one key to the next. The keycap itself is slightly smaller (around 18 mm at the base) so keys do not rub together.
Can I use a 7U spacebar on a 6.25U keyboard?
No. The stabilizer mounting points do not line up: 6.25U uses 100 mm spacing while 7U uses 114.3 mm, and the widths are different, so the modifier keys would not fit either. You need the size your bottom row was designed for.
How do I know what size spacebar I need?
Measure your existing spacebar edge to edge in millimetres and divide by 19.05 to get the size in units. About 119 mm is 6.25U, about 133 mm is 7U, about 114 mm is 6U. You can also check the stabilizer spacing underneath against the chart above.
Why does my spacebar rattle or sound different from other keys?
Spacebars need stabilizers to stay level, and an unlubed or loose stabilizer wire rattles. Their large hollow shape also amplifies sound. Lubing the stabilizer wire with dielectric grease fixes most rattle, and a little foam inside the keycap tames the hollow tone.
What is the difference between Cherry and Costar stabilizers?
Cherry stabilizers use plastic stems that insert into sockets under the spacebar and are the modern standard. Costar stabilizers use a metal wire that clips into hooks moulded into the keycap. The two are not interchangeable, so check the underside of your spacebar before buying.
Can I use a spacebar from a different brand?
Yes, as long as the size and stabilizer type match. Most 6.25U Cherry-compatible spacebars swap freely between brands. The only thing to watch is profile, since a spacebar from a different profile will sit at a slightly different height than your other keys.
Can I mix a PBT spacebar with ABS keycaps?
Yes, and plenty of people do it for durability, since the spacebar is the key your thumb wears fastest. Just match the profile so the height lines up, and expect a slightly different sound and texture from the rest of the board.
We keep our keycap reference guides updated as new profiles and layouts appear.