The best SDS max drill bits, compared.
Top pick: Keewaki 20 x 400 mm – Highest score in this set, 4.8 from 53 ratings, with its own image. The written reviews are from the United States, and the length is printed as both 400 mm and 340 mm. Best value: UK Drills 18 x 330 mm – Lowest price here for an 18 mm hole, about £14.89, and the only UK Drills size in this set with a taper point and 118 degrees on the spec. Updated October 2026.
An SDS max drill bit is a carbide-tipped masonry bit with a shank about 18 mm across. You buy one in the UK when you already own a rotary hammer over about 5 kg, or when the hole is larger or deeper than a light hammer should drill. It does not fit an SDS plus chuck. That chuck takes a shank about 10 mm, and the two systems do not interchange. The title has to say SDS max, not a bare SDS. Match the diameter to the fixing, not to the shank. Keep total length and working length apart, because one printed number is not the hole depth. Concrete, brick and block are the job. Wood and metal are not. A four-cutter or cross tip is a maker's claim for harder concrete and rebar contact, not a measured life and not a certificate for a structural anchor. Confirm the shank, the diameter, a length you can read and a flute that clears dust. Use the guide to [shank, diameter and length](/hub/drilling-and-accessories/sds-max-drill-bit/sub/sds-max-drill-bit-buying-guide) for those checks.
An SDS max drill bit is a carbide-tipped masonry bit with a shank about 18 mm across.
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Personal buying guide
Question 1 of 2
What diameter does the fixing need?
Keewaki B0GVMJM9HP is a single 20 mm SDS max cross-tip bit at about £17.99, part number K-020400, 650 g, made in China. The title says 400 mm. One bullet says 340 mm. The highlight says a 400 mm working depth and a 4-cutter head. The bullets say an 18 mm SDS max shank only, not a 10 mm SDS plus shank. The star line is 4.8 from 53. The written reviews in the file are from the United States, and most name other sizes, so that star line is not a British test of this 20 mm bit. It is the highest score in this set. It does not state a flute count, a finish or a PGM mark.
Pros
Cons
Best for: A 20 mm hole in concrete, brick or masonry on an SDS max hammer
Less suitable: An SDS plus chuck, a job that needs one agreed length, or a specified structural anchor
Specifications
Common questions
Will this fit an SDS plus drill?
The listing says it fits an 18 mm SDS max shank only, and not a 10 mm SDS plus shank.
Is the bit 400 mm or 340 mm?
The title, part number K-020400 and the included-components line say 20 mm by 400 mm. One bullet says the overall length is extended to 340 mm. The highlight says an extended 400 mm working depth. Do not quote one working length.
Do the 53 reviews describe this 20 mm bit?
The star line is 4.8 from 53. Every written review in the saved listing is from the United States, and most name other sizes, especially 1/2 in by 13 in.
UK Drills B01N8S4VO9 is a single 18 mm by 330 mm SDS max bit at about £14.89. It is the only size in this set with a taper point, a 118 degree cutting angle and a minimum bore of 18 mm on the spec. The bullets say four cutting edges and an 18 mm SDS max shank, not SDS plus. The spec says two spiral flutes, uncoated, and stone, while the bullets also name concrete, brick and block. Working length is not split out. The 4.1 from 233 is shared with the other UK Drills sizes. One review in that shared text names an 18 mm bit that sheared. It is the best value here when the hole you need is 18 mm.
Pros
Cons
Best for: An 18 mm clearance hole when you want the lowest price in this set for that diameter
Less suitable: Anyone who needs a separate working length, or who reads the shared 4.1 score as a test of this size alone
Specifications
Common questions
Will it fit an SDS plus chuck?
The bullets say SDS max hammer drills only, with an 18 mm shank, and that it does not fit SDS plus.
What size is this listing?
18 mm by 330 mm, one bit. The spec also lists a minimum bore of 18 mm, a taper point and a 118 degree cutting angle. Working length is not split out.
Are the 233 reviews only for this 18 mm bit?
The same review text is on the other UK Drills sizes. One review names an 18 mm bit that sheared in half. Others name a 38 mm hole and a 12 mm by 400 mm advert.
UK Drills B01N410BGL is a single 10 mm by 280 mm SDS max bit at about £9.99. The bullets say an 18 mm SDS max shank, not SDS plus, and a carbide cross head with four cutting edges. The spec says tungsten carbide, uncoated, two spiral flutes and a concrete surface. The size line is 10 mm by 280 mm. Working length is not given separately. The star line is 4.1 from 233, the same text as the other UK Drills sizes, and no review names this size. The same product image is used on those other sizes. It is the lowest shelf price in this set, and it is still a 10 mm hole on an 18 mm shank. A 10 mm plug hole is often an SDS plus job.
Pros
Cons
Best for: A 10 mm hole only when the hammer is already SDS max and the fixing is 10 mm
Less suitable: A 10 mm plug hole on an SDS plus drill, or a reader treating the shared reviews as a test of this size
Specifications
Common questions
Will this 10 mm bit fit an SDS plus drill?
No. The bullets say an SDS max hammer only, with an 18 mm shank, and that it does not fit SDS plus. The 10 mm figure is the cutting diameter, not the shank.
How long is it?
The size bullet says 10 mm by 280 mm, one bit. Working length is not given separately.
Are the 233 reviews for this size?
The same review text and the same 4.1 from 233 are on the other UK Drills sizes in this set. None of those reviews names 10 mm by 280 mm.
UK Drills B01MXLCTNH is a single 18 mm by 400 mm SDS max bit at about £15.99, part number 49.180400W, 520 g. The bullets say a carbide cross head with four cutting edges and an 18 mm SDS max shank. The spec says tungsten carbide, uncoated, two spiral flutes and concrete. Working length is not split out. The 4.1 from 233 is the shared UK Drills text, and no review names 18 mm by 400 mm. One shared review names a 12 mm by 400 mm advert. It costs about £1.10 more than the 18 mm by 330 mm listing. Choose it when you need that longer stated length and you accept that the length is one number.
Pros
Cons
Best for: An 18 mm hole when the length on the listing you need is 400 mm
Less suitable: Anyone who needs a stated working length, or a 20 mm or 25 mm fixing
Specifications
Common questions
Will it fit SDS plus?
The bullets say SDS max hammer drills only, 18 mm shank, and that it does not fit SDS plus.
Is 400 mm the hole depth?
The size line says 18 mm by 400 mm long. It does not give a separate working length.
Are the 233 reviews for this length?
The same text is on the other three UK Drills sizes. No review names 18 mm by 400 mm. One review is about a 12 mm by 400 mm advert whose shank would not fit a domestic drill.
UK Drills B01MQJ434H is a single 25 mm by 550 mm SDS max bit at about £26.99, 840 g, part number 49.250550W. The spec finish is a polished, dry rust-resistant coating. The other UK Drills sizes here say uncoated. The bullets say four cutting edges and an 18 mm SDS max shank, not SDS plus. The spec says two spiral flutes and a concrete surface. Working length is not split out. The 4.1 from 233 is shared, and no review names this size. Tip breakage and shank-too-wide returns sit in that shared text. It is the largest diameter and the longest stated length in this set. It does not state a PGM mark.
Pros
Cons
Best for: A 25 mm hole when you need the longest stated length in this set
Less suitable: A short hole, a tight budget, or a specification that names a PGM bit
Specifications
Common questions
Will it fit SDS plus?
The bullets say SDS max only, with an 18 mm shank, and that it does not fit SDS plus.
What finish does the spec give?
A polished, dry rust-resistant coating. The other UK Drills sizes in this set say uncoated. The bullets still say a carbide cross head with four cutting edges, and the spec says two spiral flutes.
Do the 233 reviews cover 25 mm by 550 mm?
The same review block is on the other UK Drills sizes. None names 25 mm by 550 mm. Tip breakage and shank-too-wide returns are in that shared text.
Five SDS max drill bit listings on amazon.co.uk are compared here. The score uses the shelf price, the star line on that listing, and whether shank, diameter, length and conflicts are stated in public view. There is no lab test. The weights follow the buying order: shank, diameter, length, cutter, then how clear the listing and the reviews are.
Shank
25%The listing has to say SDS max, about 18 mm, and that the bit does not fit an SDS plus chuck.
Diameter
20%The cutting diameter has to match the fixing. A 10 mm hole is often an SDS plus job even when an SDS max bit of that size exists.
Length
20%Total length and working length have to be readable as separate figures. One number on a title is not the hole depth.
Cutter and material
20%Concrete, brick and block are the job. A cross tip or four-cutter line is a manufacturer claim, not a measured life.
Listing evidence
15%A shared review pool, a length clash, or a missing flute or finish lowers confidence in that listing.
Choose an SDS max drill bit by the chuck you already own, then by the hole. The shank has to be SDS max, about 18 mm, and the listing has to say it does not fit SDS plus. Match the diameter to the fixing. A 10 mm hole is often an SDS plus job even when an SDS max bit of that size exists. Read length as total length unless the listing also prints a working length. Concrete, brick and block are the materials. A four-cutter claim is not a life test and not a rebar warranty.
An SDS max drill bit is the masonry bit for the larger of the two common SDS chucks. The shank is about 18 mm. It locks into a rotary hammer that is typically over about 5 kg. An SDS plus bit uses a shank about 10 mm. The bits do not interchange, even when a title only says SDS. If you are unsure which chuck you have, read [SDS max and SDS plus](/hub/drilling-and-accessories/sds-max-drill-bit/sub/sds-max-drill-bit-vs-sds-plus) before you order.
The shanks are about 18 mm and about 10 mm. They do not fit each other. A 10 mm cutting diameter does not make the shank SDS plus. Check the hammer before you match the hole.
Total length and working length are different. One figure on a title is not a working length. The 20 mm listing in this set prints both 400 mm and 340 mm, so do not quote a single depth for it.
A four-cutter claim on a bit in this price band is a manufacturer line, not a measured life. Shared reviews on the UK Drills sizes include tip breakage. Stop if a bit has snapped in the hole.
The first check is the shank. The listing has to say SDS max, about 18 mm, and that the bit does not fit SDS plus. A published shank guide separates a shank about 10 mm for SDS plus from a shank about 18 mm for SDS max, and it ties SDS max to the heavier hammer. A cutting diameter of 10 mm does not mean the shank is 10 mm. In this set the 10 mm bit still quotes an 18 mm SDS max shank. Published SDS max ranges from Bosch start at 12 mm, and a 10 mm plug hole is often an SDS plus job.
Length is the check most of these listings fail to split. Separate total length from working length. Bosch prints both on its SDS max bits. Several amazon.co.uk titles print one number, and that number is not automatically the depth of the hole. In this set the UK Drills sizes give 280 mm, 330 mm, 400 mm or 550 mm as a single figure, with working length not split out.
Three typical situations, each with a recommendation from this comparison.
You already own an SDS max rotary hammer and you need one diameter and one length, not a set. If that fixing is 20 mm, the Keewaki listing is the only match in this set. Read the 400 mm title and the 340 mm bullet before you treat either figure as depth.
You drill larger holes in concrete and you have to decide whether a budget four-cutter claim is enough. The 25 mm by 550 mm UK Drills bit is the largest and longest listing here. It is not a named trade bit, and it does not state a PGM mark.
You searched SDS and you may actually need SDS plus, especially for a 10 mm plug hole. An SDS max bit will not fit that chuck. The 10 mm listing here still quotes an 18 mm SDS max shank. Use it only if the hammer is SDS max and the fixing really is 10 mm.
The highest score in this set is the Keewaki 20 mm bit, at about £17.99, with 4.8 from 53 ratings. That is the top pick if you need 20 mm and you can accept a title that says 400 mm and a bullet that says 340 mm. The best value for an 18 mm hole is the UK Drills 18 mm by 330 mm bit at about £14.89, the only size here with a taper point and 118 degrees on the spec. The cheaper 10 mm bit is a small hole on an 18 mm shank, and a 10 mm plug hole is often an SDS plus job. None of these listings is a lab test or a PGM-marked anchor bit.
Keewaki 20 x 400 mm
Highest score in this set, 4.8 from 53 ratings, with its own image. The written reviews are from the United States, and the length is printed as both 400 mm and 340 mm.
UK Drills 18 x 330 mm
Lowest price here for an 18 mm hole, about £14.89, and the only UK Drills size in this set with a taper point and 118 degrees on the spec.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK and manufacturer pages used for shank, dust, vibration and anchor-bit geometry, plus the amazon.co.uk listings for the five ASINs. Last checked on 22 October 2026.
Expert source (DIY & tools): Charlie White (Charlie DIYte) (external profile) – public expert commentary used as a research source, not as a contributor to our pages.
This article contains affiliate links. If you buy through these links we may earn a small commission, at no extra cost to you. Prices and star ratings come from the amazon.co.uk listings. This comparison is not a lab test.
