SDS drill bit sizes: SDS-Plus vs SDS-Max, the full reference
SDS (Special Direct System) is the slotted-shank family that rotary hammers use, introduced by Bosch in 1975 to let a bit float axially in the chuck so the hammer mechanism strikes the bit directly instead of the whole chuck assembly [6] [1]. That is what separates SDS bits from ordinary masonry bits: a plain masonry bit has a round or hex shank clamped in a 3-jaw chuck (those size runs are on our masonry bit size chart), while an SDS bit has machined grooves that lock into a rotary hammer and carry far harder blows. This page is the size reference for both SDS worlds: the shank standards, the diameter ranges, the length series, the energy classes that tie bits to hammers, and the plug and anchor sizes each bit diameter serves. Every row cites two or more named sources.
The one-minute answer
- SDS-Plus: 10 mm shank, about 40 mm insertion, four grooves (two open, two closed), bit diameters roughly 4 to 30 mm, hammers around 1.5 to 4 J [1] [2].
- SDS-Max: 18 mm shank, 90 mm insertion, five grooves (three open, two closed), bit diameters roughly 12 to 52 mm, hammers from 5 J to 20 J and beyond [1] [3].
- They do not interchange in either direction: different diameters, different groove counts, different insertion depths [1] [2].
- Almost every cordless rotary hammer (Milwaukee M18 Fuel, DeWalt 20V, Makita 18V LXT class) is SDS-Plus; SDS-Max is the corded big iron for 1 inch and larger holes [2] [4].
The shank chart
Three shank formats have existed under the SDS name. The original SDS (sometimes called SDS-plain) is legacy, rarely stocked new outside Europe, and functionally superseded by SDS-Plus, which kept the same 10 mm diameter but added closed locking grooves [6] [1]. The one you almost certainly own is one of the bottom two rows.
| Shank system | Shank diameter | Insertion depth | Grooves | Typical hammer energy | Sources |
|---|---|---|---|---|---|
| SDS (original, legacy) | 10 mm | about 40 mm | 2 open | 1.0 to 2.0 J | [6] [1] |
| SDS-Plus | 10 mm | about 40 mm | 4 (2 open + 2 closed) | 1.5 to 4.0 J | [1] [2] |
| SDS-Max | 18 mm | 90 mm | 5 (3 open + 2 closed) | 5.0 to 20+ J | [1] [2] |
The groove count is the part worth remembering because it explains the non-interchange: the chuck's drive balls and keys engage those grooves, so an SDS-Plus bit physically cannot seat in an SDS-Max chuck (it falls through) and an SDS-Max shank cannot enter an SDS-Plus chuck at all [1] [2]. The SDS-Plus shank geometry itself is standardized under ISO 6480-1 (historically DIN 8035), with the cylindrical lands held to an h9 tolerance, which is why bits and chucks cross brands freely within each system [4] [6].
Diameter ranges: what each system drills
Published ranges differ at the edges by brand and catalog, so the table gives the honest spread rather than a single false-precise number. The short version: SDS-Plus is a 4 to 30 mm world that lives mostly between 6 and 20 mm, and SDS-Max starts where Plus thins out and runs to 50 mm and beyond [1] [12].
| System | Range per Wryno Global | Range per Bridge Fasteners | Most common sizes | Sources |
|---|---|---|---|---|
| SDS-Plus | 4 to 32 mm | 4 to 30 mm | 6, 8, 10, 12 mm | [1] [12] |
| SDS-Max | 12 to 52 mm | 13 to 44 mm | 16 to 40 mm | [1] [12] |
Retail listings confirm both ends: Faithfull's SDS-Plus line runs 4 to 20 mm in standard catalogs, Lilley's Premier Diamond Site Tuff series spans 5 to 32 mm including resin-anchor sizes, and the Swiftfix SDS-Max program runs 12 to 50 mm in 1 mm steps for the popular middle [7] [9] [10]. Specialty SDS-Max production runs to 65 mm and beyond at the manufacturer level [3] [4].
The overlap zone: 20 to 26 mm
Both systems sell bits between roughly 20 and 26 mm, and this is the only range with a real buying decision inside it. The industry rule of thumb is to switch from SDS-Plus to SDS-Max above 26 mm; in hard or heavily reinforced concrete the practical crossover drops toward 20 mm because a 10 mm Plus shank driven at high joule ratings fatigues, while an 18 mm Max shank spreads the same energy over more than double the contact length [3] [4]. Tool Army frames the same zone in inches: bits from 1 to 1-1/4 inch exist in both systems and either can do the job, below that Plus is faster and lighter, above it Max is the only efficient choice [2] [4].
Length series: overall length vs working length
Two length numbers appear on every SDS bit, and confusing them is the most common ordering mistake. Overall length (OAL) runs from carbide tip to the end of the shank; working length (WL, also flute length) is the fluted part that actually cuts, and it is all that matters for hole depth. On standard SDS-Plus bits the working length runs roughly 60 to 65 mm behind the overall length, so a 160 mm OAL bit drills only about 100 mm [5] [8]. The 110 mm OAL bit deserves its own warning: with only about 50 mm of working length it cannot reach the embedment depth of any standard expansion anchor in concrete, and is really a shallow-plug and tile-starter bit [5] [7].
| Overall length | Working length (Heller, Faithfull) | Working length (Premier Diamond) | Deep enough for | Sources |
|---|---|---|---|---|
| 110 | 50 | 50 | shallow plugs in soft block only | [7] [8] |
| 160 | 100 | 100 | M6 to M8 anchors, general fixings | [7] [8] |
| 210 | 150 | 150 | M8 to M12 anchors, through-block runs | [7] [9] |
| 260 | 200 | 200 | M16 to M20 sleeves, deep screeds | [7] [8] |
| 310 | 250 | 250 | M20+ structural anchors | [8] [9] |
| 400 to 460 | 340 to 400 | 400 | through-wall penetrations | [7] [9] |
| 1000 | 940 | 940 | specialist deep holes | [9] [8] |
SDS-Max lengths are chunkier because the 90 mm insertion eats more of the bar. The Swiftfix program and Makita's own listings agree on the shape of the series:
| Overall length | Working length (Swiftfix) | Working length (Makita D-33984 class) | Notes | Sources |
|---|---|---|---|---|
| 340 | 200 | 200 class | standard anchor work | [10] [11] |
| 520 to 540 | 400 | 400 | through-wall and deep anchors | [10] [11] |
| 920 to 940 | 800 | 800 class | deep penetrations | [10] [11] |
| 1320 | 1200 | 1200 class | 22 mm and up diameters only | [10] [11] |
Energy class: match the bit to the hammer
Shank format is set by the tool you own, not by preference, but the energy table explains why the ranges differ. A compact SDS-Plus hammer delivers 1.5 to 4 J per blow and weighs 2 to 5 kg; an SDS-Max rotary hammer starts around 5 J, commonly spans 8 to 12 J, and runs to 20 J and beyond in demolition-class machines weighing 6 to 12 kg [1] [2]. Bit makers publish minimum hammer energies per diameter on the Max side, from about 3 J at 14 mm to 12 J at 80 mm in the Zhonghuan reference chart, which is the same physics statement from the bit's point of view [3] [4]. The practical consequences: run Plus-size holes on Plus hammers and Max-size holes on Max hammers, and when a big-hole job is occasional, renting the SDS-Max tool beats owning it [2] [6].
| System | Impact energy class | Typical tool weight | Tool class | Sources |
|---|---|---|---|---|
| SDS-Plus | 1.5 to 4.0 J | 2 to 5 kg | cordless and compact corded rotary hammers | [1] [2] |
| SDS-Max | 5.0 to 20+ J | 6 to 12+ kg | corded rotary hammers, breaker class | [1] [2] |
Plug and anchor to bit size mapping
This is the question most SDS searches are really asking: which bit diameter serves which fixing. For plastic wall plugs the rule is one line, the bit diameter equals the plug diameter, and the colour code carries the size [13] [14].
| Plug colour | Plug diameter | SDS-Plus bit | Screw gauge | Screw diameter | Sources |
|---|---|---|---|---|---|
| Yellow | 5 mm | 5.0 mm | No. 4 to 8 | 3.0 to 4.0 mm | [13] [14] |
| Red | 6 mm | 6.0 mm | No. 6 to 10 | 3.5 to 5.0 mm | [13] [14] |
| Brown | 7 mm | 7.0 mm | No. 8 to 14 | 4.0 to 6.0 mm | [13] [14] |
| Blue | 10 mm | 10.0 mm | No. 14 and up | 6.0 to 8.0 mm | [13] [14] |
Colours are a convention, not a standard: brands occasionally shift them, so the printed diameter on the box wins over the colour when they disagree [13] [14]. Two depth rules from the same guides: drill about 10 mm deeper than the plug length so dust has somewhere to go, and pick a screw 1 to 2 mm smaller than the plug so it expands the plug instead of splitting it [14] [13].
For steel anchors the mapping is to the bolt's nominal diameter: an M8 through bolt or sleeve anchor wants an 8 mm hole, M10 wants 10 mm, M12 wants 12 mm, all comfortably inside SDS-Plus territory, while heavy sleeve anchors from 16 mm up cross into the overlap zone where either shank works but Max clears dust faster [13] [4]. The US side of that question, Tapcon screws and their 1/4 inch ANSI bits, has its own table on our concrete anchor bit size page. And if the hole is really a core hole, 30 mm and up through-work, an SDS-Max core bit or a dedicated core rig is the tool, not a solid bit [3] [12].
Buying rules, compressed
Know the shank before shopping: it is printed on the tool or obvious from the chuck (10 mm slotted is Plus, 18 mm slotted is Max), and it fixes the system [1] [2]. Buy diameters, not sets: the plug table above means 5, 6, 7, 8, 10, and 12 mm Plus bits cover essentially all fixing work, with one long 210 or 260 mm bit in 8 mm for through-block runs [13] [7]. Order by working length when depth matters, since OAL overstates drilling depth by the 60 to 65 mm the chuck swallows [5] [8]. For anything above 26 mm in cured or reinforced concrete, or repeated 1 inch work, that is SDS-Max territory and usually a rental [2] [3].
Related
For round and hex shank masonry bits that fit ordinary 3-jaw hammer drills, the masonry bit size chart covers the inch and mm runs and the shank decoder. For the tools themselves, hammer drill vs regular drill explains why SDS rotary hammers hit harder than any hammer drill, and the best drills for concrete ranks the dataset's hammer-capable models. For US-style concrete anchors and their bit rules, concrete anchor bit sizes; for choosing bits across materials, drill bits by material.
Sources
- Wryno Global, SDS vs SDS Plus vs SDS Max Complete Comparison: shank diameters 10/18 mm, insertion depths 40/90 mm, slot counts, diameter ranges 4-32 and 12-52 mm, energy classes 1.5-4 J and 5-20+ J, tool weights 2-5 and 6-12+ kg (wrynoglobal.com/sds-vs-sds-plus-vs-sds-max/)
- Tool Army Company, SDS Plus vs SDS Max: groove counts 2+2 vs 3+2, non-interchangeability, crossover zone 1 to 1-1/4 in, cordless Milwaukee/DeWalt tools are SDS-Plus, rental guidance for Max (toolarmycompany.com/blogs/universal/sds-plus-vs-sds-max)
- Zhonghuan Tools, SDS-Max Drill Bit Size Chart: 14-80 mm diameter table with OAL/WL series 200-600 mm, minimum hammer energies 3-12 J, 18 mm shank 90 mm insertion, overlap zone 20-26 mm, specialty diameters to 65 mm (zhonghuantools.com/en/resources/sds-max-drill-bit-size-chart)
- Zhonghuan Tools, SDS-Plus vs SDS-Max Engineer's Decision Guide: 6-25 mm practical Plus domain, ISO 6480-1 shank standardization, hard-concrete crossover near 20 mm, 18 mm shank 5-groove layout (zhonghuantools.com/en/resources/sds-comparison-guide)
- Zhonghuan Tools, SDS Plus Drill Bit Length Guide: OAL vs working length definition, WL roughly OAL minus 65 mm, the 110 mm bit as a shallow-work specialist, length-to-anchor-mapping by WL (zhonghuantools.com/en/resources/sds-plus-drill-bit-length-guide)
- Industrial Monitor Direct, Selecting SDS Hammer Drill Chucks: Bosch 1975 origin of SDS, original SDS 10 mm 2-open-slot legacy format, parameter comparison table, spline-drive alternatives (industrialmonitordirect.com/blogs/knowledgebase/selecting-sds-hammer-drill-chucks-sds-plus-vs-sds-max-compared)
- Faithfull Tools, SDS Masonry Drill Bits catalog: diameter and OAL/WL table 4-20 mm, 110 mm OAL with 50 mm WL through 600 mm OAL with 540 mm WL (faithfulltools.com/p/FAISDS4160/SDS-Masonry-Drill-Bits)
- RJ Fixings, Heller TriJet SDS-Plus range: OAL/WL pairs 110/50, 160/100, 210/150, 260/200, 310/250, 450/400, 600/550 mm (rjfixings.shop/heller-trijet-sds-plus-drill-bit-range)
- Lilley Tile and Stone, Premier Diamond Site Tuff SDS-Plus drills: 5-32 mm including resin anchor sizes, OAL/WL series 110/50 through 1000/940 mm (lilleytileandstone.co.uk)
- Swiftfix Timber Fixings, SDS Max drill bits: 12-50 mm in 1 mm steps, OAL/WL 340/200, 520-540/400, 920-940/800, 1320/1200 mm by diameter (timberfixings.com/sds-max-drill-bits/)
- Makita UK, D-33984 TCT drill bit 20 x 400/540 mm SDS-Max and P-17049 12 x 400/540 mm SDS-Max: OAL 540 mm, WL 400 mm, 2-cutter concrete bits (makitauk.com/product/d-33984.html)
- Bridge Fasteners, Difference Between SDS, SDS-Plus and SDS-Max Drills: SDS-Plus 10 mm shank 4-30 mm bits, SDS-Max 18 mm shank 13-44 mm bits (bridgefasteners.com/blogs/article/difference-between-sds-sds-plus-and-sds-max-drills)
- Tool Compatibility, Wall Plug Size Chart UK: yellow 5, red 6, brown 7, blue 10 mm plugs with matching drill and screw sizes, colour-code caveat, hole 10 mm deeper than plug (toolcompatibility.com/wall-plug-size-chart/)
- BuildWiz UK, Wall Plugs Rawlplugs Size Matching Guide: plug diameter equals drill diameter, screw 1-2 mm under plug diameter, red 6 mm with No. 8 and brown 7 mm with No. 10 as the two most common pairs (buildwiz.uk/knowledge/materials/fixings/wall-plugs)