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Buying a replacement spacebar only works if you get the size right. Spacebars are measured in units (U), and the size you need depends on your keyboard’s bottom row, not on how big the board is overall. Below you’ll find the full size chart, the stabilizer spacing for each size, and how to measure the spacebar you already have. It also explains why your ruler will read about a millimetre short.
⚡ Quick answer
One keyboard unit (1U) is 19.05 mm. The most common spacebar is 6.25U, a 119.06 mm layout footprint, used on standard ANSI keyboards, with stabilizer stems 100 mm apart. The other common sizes are 7U (133.35 mm) and 6U (114.3 mm). The keycap itself measures roughly 1 mm less than its footprint, so a 6.25U spacebar reads about 118 mm on a ruler. Measure, divide by 19.05, and round up to the nearest standard size.
🏆 Top picks for a spacebar upgrade
- Replacement spacebar or full set: PBT keycap sets with 6.25U and 7U spacebars. PBT resists the shine your thumb wears into a spacebar.
- Fix a rattly spacebar: Durock V2 screw-in stabilizers, the usual upgrade for Cherry-style boards.
- Lube for the stabilizer wire: Krytox GPL 205g0, plus dielectric grease for the wire ends.
- Get the old one off safely: a wire keycap puller, which will not scratch the keycap or bend the stabilizer.
Affiliate links: if you buy through them we may earn a small commission at no extra cost to you.
Spacebar size chart
The footprint is the space the key occupies in the layout (units × 19.05 mm). The measured keycap column is what a ruler typically reads across the base of the cap, which is slightly narrower so neighbouring keys don’t rub. Stabilizer spacing is the centre-to-centre distance between the two stabilizer stems.
| Size | Footprint (mm) | Footprint (in) | Measured keycap (approx.) | Stabilizer spacing | Where you find it |
|---|---|---|---|---|---|
| 7U | 133.35 mm | 5.25 in | ≈132 mm | 114.3 mm | 7U (Tsangan/WKL) bottom rows, many customs |
| 6.5U | 123.83 mm | 4.88 in | ≈123 mm | Varies by board | Occasional European and custom layouts |
| 6.25U | 119.06 mm | 4.69 in | ≈118 mm | 100 mm | Standard ANSI and ISO, most keyboards |
| 6U | 114.3 mm | 4.50 in | ≈113 mm | 95.25 mm (check stem position) | Some 60% boards, vintage layouts |
| 5.5U | 104.78 mm | 4.13 in | ≈104 mm | Varies by board | Some ergonomic and Alice-style layouts |
| 4U | 76.2 mm | 3.00 in | ≈75 mm | Varies by board | Compact and 40% layouts |
| 3U | 57.15 mm | 2.25 in | ≈56 mm | Usually a 2U stabilizer (23.8 mm) | Split-spacebar layouts |
| 2.75U | 52.39 mm | 2.06 in | ≈51 mm | 2U stabilizer (23.8 mm) | Split spacebars, right Shift |
| 2.25U | 42.86 mm | 1.69 in | ≈42 mm | 2U stabilizer (23.8 mm) | Split spacebars, left Shift, Enter |
📌 The quick rule. Measured width in millimetres ÷ 19.05, then round up to the nearest size in the chart. A cap reading 118 mm gives 6.19, which is a 6.25U spacebar; 132 mm gives 6.93, which is 7U. Rounding down is how people end up ordering 6U by mistake.
Layout footprint vs measured keycap width
Size charts, including ours, list the footprint: 6.25 × 19.05 = 119.06 mm. That is the slot in the layout, measured from the centre of the gap on one side to the centre of the gap on the other. The plastic keycap is deliberately smaller so it never touches its neighbours. On most profiles the base of a 1U cap measures around 18.1–18.4 mm, so a spacebar loses roughly 0.7–1 mm against its footprint.
Two practical consequences. First, don’t treat a measurement of 118 mm as a mystery size. It’s a normal 6.25U cap. Second, measure at the base, not the top. Sculpted profiles like SA and Cherry taper towards the top surface, so measuring the top can read several millimetres short. The stabilizer spacing is the more reliable check, because it’s fixed by the stabilizer hardware rather than the keycap maker.
What does 7U mean?
7U means a key seven units wide: 7 × 19.05 = 133.35 mm of layout footprint. In practice it almost always refers to a 7U spacebar and the bottom row built around it, where the modifiers are 1.5U, 1U and 1.5U on each side instead of the standard row of 1.25U keys. That arrangement is usually called a Tsangan bottom row. A 7U spacebar uses stabilizers 114.3 mm apart, so it can’t go on a board with 6.25U stabilizers.
The three sizes that matter most
6.25U, the standard
This is what the vast majority of keyboards use, in both ANSI and ISO layouts. The bottom row runs 1.25U modifiers on either side of the spacebar. Replacement 6.25U spacebars are the easiest to find in any keycap set, colour or material.
- Footprint: 119.06 mm (6.25 × 19.05); measures ≈118 mm
- 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 is still popular on custom keyboards. Keycap sets support it less often, so check that the set’s kit list includes a 7U spacebar and the 1.5U modifiers before you buy.
- Footprint: 133.35 mm (7 × 19.05); measures ≈132 mm
- 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. It catches people out because a 6U bottom row shifts the modifier positions, and few keycap sets include the right kit. Some 6U spacebars also have the switch stem off-centre rather than in the middle, and a centred-stem 6U cap won’t fit a board built for the offset version, or the other way round. Turn yours over and note where the centre stem sits before ordering.
- Footprint: 114.3 mm (6 × 19.05); measures ≈113 mm
- Stabilizers: commonly 95.25 mm apart, but confirm against your board
7U vs 6.25U: the comparison people actually need
Both bottom rows total exactly 15U. The spacebar and the modifiers around it are simply divided differently.
| 6.25U row | 7U row | |
|---|---|---|
| Spacebar | 6.25U (119.06 mm) | 7U (133.35 mm) |
| Modifiers | Seven keys, all 1.25U | Six keys: 1.5U, 1U, 1.5U each side |
| Row total | 15U | 15U |
| Stabilizers | 100 mm apart | 114.3 mm apart |
| Keycap support | Nearly every set | Often needs a separate kit |
Because both rows come to 15U, some PCBs and plates support either. The hardware is not interchangeable, though: the stabilizers sit 14.3 mm further apart on a 7U layout, so a 6.25U spacebar can’t mount on 7U stabilizers, and the modifier keycaps are different widths too.
📌 If you’re choosing: pick 6.25U unless you have a specific reason not to. Keycap sets support it almost universally, replacements are cheap and easy to find, and you’ll never hunt for a compatible kit. 7U feels slightly more generous under the thumb and gives a cleaner-looking bottom row. That’s the whole advantage.
Why is the spacebar so big?
It’s the most-pressed key on the board. In ordinary English text roughly one keystroke in six is a space, more than any single letter. It’s pressed by a thumb, the least precise digit, which approaches from below and needs a wide landing area that both thumbs can reach from the home row. And it fills the space left over: the bottom row must be as wide as the rows above it, so once the modifiers are placed the spacebar absorbs whatever width remains.
What size spacebar does my keyboard use?
Board size and spacebar size are largely independent. A 60% keyboard usually has the same spacebar as a full-size one, because compact layouts remove keys from the edges rather than shrinking the bottom row.
| Keyboard | Usual spacebar |
|---|---|
| Full-size, TKL, 75%, 65% (ANSI or ISO) | 6.25U |
| 60% | 6.25U, occasionally 6U or 7U |
| 40% and compact | 4U or smaller, sometimes split |
| Alice-style and ergonomic | Split, often 2.25U plus 2.75U |
| JIS (Japanese) boards | Much shorter, with conversion keys either side |
ISO and ANSI boards share the same 6.25U spacebar; the differences are at Enter and left Shift. JIS boards are the exception, with a short spacebar that standard sets don’t cover. Our keyboard layouts guide shows how to tell the three apart, and the keyboard sizes guide covers form factors.
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 don’t bend the stabilizer wire.
- Measure the base, edge to edge, with the spacebar face down. Calipers are more accurate; a ruler is close enough.
- Divide by 19.05 and round up to the nearest size in the chart. Expect your reading to be about 1 mm under the footprint.
- Measure the stabilizer stems centre to centre underneath and match them to the chart. This is the most reliable check.
- Note where the switch stem sits. Centred is normal; off-centre means you need a matching offset spacebar.
💡 Faster shortcut. Count the keys either side of your spacebar. If they’re all the same small width (1.25U), you have a 6.25U spacebar. If the outer ones are noticeably wider with a narrow key between them, you’re looking at a 7U bottom row.
Check your exact model before you order
Measurements get you close; your keyboard’s documentation settles it. Before buying a spacebar or a full set, confirm the size against at least one of these for your exact model and revision. Manufacturers do change bottom rows between versions.
- The manufacturer’s product page or manual. Look for a layout diagram or a keycap-size list, not a marketing photo.
- The PCB or plate layout options for custom kits. These list which bottom rows (6.25U, 7U, split) the board supports.
- The VIA or QMK layout for boards that use them. It shows every key width in the bottom row.
- The keycap set’s kit list. Check it includes your spacebar size and your modifier sizes, since a 7U spacebar is useless without 1.5U and 1U modifiers.
Stabilizers: Cherry vs Costar
Size is only half the compatibility question. The other half is the stabilizer mount your spacebar is designed for, and you can tell by turning it over.
- Cherry style uses plastic stems that push into cross-shaped sockets on the underside of the spacebar. Almost every modern keyboard and keycap set uses it.
- Costar style uses a metal wire that clips into inserts or hooks near the ends of the spacebar. Found on some older and prebuilt boards. Costar and Cherry spacebars are not interchangeable.
Most replacement spacebars sold today are Cherry-compatible. If yours rattles or binds after a swap, our keyboard stabilizers guide walks through tuning and lubing them.
Installing a spacebar properly
- Lube the stabilizers first. It’s much easier with the spacebar off and makes the biggest difference to how it sounds. See our stabilizer 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 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; check the stabilizers are fully seated |
| Sticking or binding | Misaligned stems or wrong size | Reseat the spacebar; confirm size and stabilizer spacing match 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 thin foam or felt strip inside the spacebar, or case foam |
| Sits crooked | Warped keycap, offset stem mismatch or uneven stabilizers | Check it sits flat on a table; confirm the stem position matches; 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: a 119.06 mm layout footprint (6.25 × 19.05 mm), with the keycap itself measuring about 118 mm. It’s used on most ANSI and ISO keyboards, with stabilizers 100 mm apart. Other common sizes are 7U (133.35 mm) and 6U (114.3 mm).
What does 7U mean on a keyboard?
7U means a key seven units wide, a 133.35 mm footprint. It usually refers to a 7U spacebar in a Tsangan-style bottom row, with 1.5U, 1U and 1.5U modifiers either side. Its stabilizers sit 114.3 mm apart, so it doesn’t fit boards built for a 6.25U spacebar.
How many mm is 1U on a keyboard?
One unit (1U) is 19.05 mm, or 0.75 inches. That’s the key pitch: the distance from the centre of one key to the next. The keycap itself is smaller, around 18.1–18.4 mm at the base, so that neighbouring keys don’t rub together.
Why does my spacebar measure 118 mm instead of 119 mm?
Because charts list the layout footprint, not the plastic. A 6.25U slot is 119.06 mm, but the keycap is made about a millimetre narrower so it clears its neighbours. A 118 mm reading is a normal 6.25U spacebar. Measure at the base, since sculpted profiles taper towards the top.
Can I use a 7U spacebar on a 6.25U keyboard?
No. The stabilizer mounts don’t line up: 6.25U uses 100 mm spacing and 7U uses 114.3 mm. The widths differ too, so the surrounding modifiers wouldn’t fit either. You need the size your bottom row, plate and PCB were built for.
What is the difference between Cherry and Costar stabilizers?
Cherry-style stabilizers use plastic stems that push into cross-shaped sockets under the spacebar, and are the modern standard. Costar-style stabilizers use a metal wire that clips into inserts near the ends of the keycap. The two aren’t interchangeable, so check the underside before buying.
What is a split spacebar?
A split spacebar replaces the single long bar with two or more smaller keys, most often a 2.25U plus a 2.75U. It appears on Alice-style and ergonomic layouts. Those pieces use ordinary 2U stabilizers (23.8 mm apart), the same as Shift keys, so the rules for a 6.25U bar don’t apply.