What size masonry drill bit does a 1/4 Tapcon need?

A 3/16 in carbide bit. Classic Tapcon masonry screws take a bit one size smaller than the screw: 3/16 in screw takes 5/32 in, 1/4 in screw takes 3/16 in. The bit must be carbide-tipped, meet ANSI B212.15-1994, and run in a hammer drill in hammer-plus-rotation mode.

What do SDS-Plus and SDS-Max mean on a masonry bit?

They are shank systems for rotary hammers, not bit quality grades. SDS-Plus is a 10 mm shank with two open and two closed slots, inserting about 40 mm, and covers bit diameters of roughly 4 to 30 mm. SDS-Max is an 18 mm shank with three open slots, inserting 70 to 90 mm, for bits of roughly 13 to 44 mm. The two are not interchangeable.

Can I use a masonry bit in a regular drill?

Yes, if the bit has a plain round or 3-flat shank, it fits the 3-jaw chuck of any drill. But masonry bits cut by hammering while they rotate, so without hammer mode the going is slow and the bit wears fast. In a pinch, small holes in soft brick or mortar go through; concrete really wants a hammer drill.

Masonry drill bit sizes: the chart in inches and mm

A masonry bit is sized by its cutting diameter, and the number you shop with depends on which shank world you live in: inch-sized round-shank bits for 3-jaw hammer drills, millimeter-sized SDS shanks for rotary hammers. Both charts are below, plus the shank-type decoder and the Tapcon bit rule that answers the most common question in the category. Every row cites two or more named sources.

Three things to know before the charts.

The diameter is the hole. A masonry bit drills a hole equal to its cutting diameter, so anchor packaging that says "drill 1/4 in" means a 1/4 in bit, no fudge either way ^{[1] [2]}.
The shank picks the tool, not the size. Round and 3-flat shanks fit any 3-jaw chuck; SDS-Plus and SDS-Max fit only their own rotary hammer chucks and do not interchange ^{[5] [6]}.
Tapcons are the exception to "bit equals hole". Classic Tapcon screws tap their own threads, so their bits run one size smaller than the screw: 3/16 in screw, 5/32 in bit ^{[10] [11]}.

Masonry bit size chart: inches, for 3-jaw hammer drills

Round-shank and 3-flat-shank carbide masonry bits are stocked in inch sizes from 1/8 in up to 1 in for tools with standard chucks. The typical set carries the small sizes; the large ones are sold individually. Diameters below are as published by the manufacturers named in each row.

Round-shank masonry drill bit sizes (inch)
Bit diameter	Where you meet it	Sources
1/8 in	Smallest commonly stocked; pin holes, small anchors	^{[1] [3]}
5/32 in	The Tapcon bit for 3/16 in screws	^{[1] [10]}
3/16 in	The Tapcon bit for 1/4 in screws; small plastic anchors	^{[1] [11]}
1/4 in	Small sleeve anchors and screws; in most sets	^{[1] [2]}
5/16 in	Larger Tapcon-style screws (3/8 in screw)	^{[2] [12]}
3/8 in	Common wedge and sleeve anchor size; in most sets	^{[1] [2]}
1/2 in	Top of most sets; matches 1/2 in wedge anchors	^{[1] [2]}
5/8 in	Sold individually; heavy anchors	^{[1] [4]}
3/4 in	Sold individually; heavy anchors, through-bolts	^{[1] [4]}
7/8 in and 1 in	Top of the round-shank range, individual bits only	^{[1] [4]}

Row sources: [1] Home Depot's listing for the Milwaukee 6-piece carbide hammer drill bit set 48-20-8856 (range stated 1/8 in to 1 in, lengths to 18 in), [2] Milwaukee's SHOCKWAVE 10-piece carbide set 48-20-9058 (1/8, 5/32, 3/16, 7/32, 1/4, 5/16, 3/8, 1/2 in contents), [3] Milwaukee's set listing via boschtools.ca context, [4] Bosch's rotary masonry line BM5202 published sizes through 1 in x 13 in, [10] Tapcon's official installation instructions, [11] ITW Red Head Tapcon product data, [12] Concrete Fastening Systems' Tapcon bit-size article.

Masonry bit size chart: millimeters, for SDS rotary hammers

SDS bits are a millimeter world. The two shank systems split the range between them, with overlap in the middle sizes where either tool can drill the hole.

SDS masonry drill bit sizes (mm)
Shank system	Bit diameter range	Most common sizes	Sources
SDS-Plus	4 to 30 mm	6, 8, 10, 12 mm for anchor work	^{[5] [6]}
SDS-Max	13 to 44 mm	1/2 in (13 mm) upward; core bits larger	^{[5] [6]}

Row sources: [5] Bridge Fasteners' SDS vs SDS-Plus vs SDS-Max guide (SDS-Plus 4 to 30 mm, SDS-Max 13 to 44 mm quoted in inch and mm), [6] GTSE's SDS drill bits explained (SDS-Plus typical 4 to 25 mm, SDS-Max 10 to 50 mm). The two guides' ranges differ slightly at the edges; both put SDS-Plus in the 4-to-30 neighborhood and SDS-Max above it.

Shank types decoded: which fits what

The shank is the part the chuck grabs, and buying the wrong one is the classic masonry-bit mistake because the sizes look similar in photos.

Masonry bit shank types
Shank	Fits	Typical bit diameters	Notes	Sources
Plain round / 3-flat	Any 3-jaw keyed or keyless chuck	1/8 to 1 in	3-flat prevents slippage under hammer load	^{[1] [7]}
1/4 in hex	Impact drivers, quick-change holders	1/8 to 1/2 in	Milwaukee SHOCKWAVE carbide line	^{[2] [8]}
SDS-Plus	SDS-Plus rotary hammers only	4 to 30 mm	10 mm shank, 2 open + 2 closed slots, about 40 mm insertion	^{[5] [6]}
SDS-Max	SDS-Max rotary hammers only	13 to 44 mm	18 mm shank, 3 open slots, 70 to 90 mm insertion	^{[5] [6]}

Row sources: [1] Milwaukee 48-20-8856 set listing (3-flat shank, 1/2 in 3-jaw chucks), [2] Milwaukee SHOCKWAVE set (1/4 in hex), [5] Bridge Fasteners SDS guide, [6] GTSE SDS guide, [7] Confast's Tapcon installation article (straight-shank bits in Jacobs-style chucks), [8] Home Depot's Milwaukee SHOCKWAVE multi-material carbide bit listing (1/8 to 5/16 in hex-shank).

The practical read on the four rows: if your tool has a normal chuck, you are in the first two rows and your sizes are inch sizes. If it is a rotary hammer, the shank is decided for you and your sizes are millimeters. An SDS-Plus bit will not seat in an SDS-Max chuck or the reverse ^{[5] [6]}, so there is no buying decision to get wrong once you know which hammer you own.

What size masonry bit for a Tapcon

Tapcon is the question this category gets asked most, and the answer is short: the bit is one size smaller than the screw. Our concrete anchor bit size chart carries the full Tapcon table with embedment and the Tapcon+ exceptions; the summary rule, confirmed by Tapcon's own installation instructions and ITW Red Head's product data ^{[10] [11]}:

Tapcon screw to bit pairing (classic)
Tapcon screw	Bit	Sources
3/16 in	5/32 in	^{[10] [11]}
1/4 in	3/16 in	^{[10] [11]}

Row sources: [10] Tapcon (ITW) official installation instructions for 3/16 in and 1/4 in diameters, [11] ITW Red Head Tapcon Anchors product data PDF. The full table with Tapcon+ same-size ANSI bits, XL screws, and embedment rules lives on the anchor chart page.

Two requirements ride along with the diameter. The bit must be carbide-tipped and meet ANSI B212.15-1994, because hole tolerance is what the screw's threads cut against ^{[9] [13]}. And it runs in a hammer drill in hammer-plus-rotation mode, never rotary-only ^{[9] [13]}. Drill the hole at least 1/4 in deeper than the embedment, and clean the dust out before driving ^{[10] [14]}.

Buying guidance that follows from the charts

Buy the anchor first, then the bit. The anchor package names the hole diameter; the bit matches it exactly. For Tapcons the package names the screw, and the bit is one size down ^{[10] [11]}.
A 6-piece inch set covers most hammer-drill work. The Milwaukee set running 1/8 to 1/2 in is the shape of the mainstream ^{[1] [2]}; sizes above 1/2 in are bought per job.
Check the chuck before shopping SDS. SDS-Plus and SDS-Max do not interchange, and neither fits a 3-jaw chuck ^{[5] [6]}.
Length matters as much as diameter. The hole needs the anchor's embedment plus clearance; Tapcon holes run 1/4 in deeper than embedment by rule ^{[10] [14]}.

Related guides

Also on this site: the concrete anchor bit size chart for the full Tapcon, wedge, and sleeve anchor tables, drill bits by material for how masonry bits differ from wood and metal bits, the best drill for concrete before you invest in a rotary hammer, and hammer drill vs regular drill for whether your current tool can drive these at all.

Sources

Home Depot, Milwaukee Carbide Hammer Drill Bit Set 6-piece 48-20-8856 (1/8 in to 1 in range, lengths to 18 in, 1/2 in 3-jaw chucks, 3-flat shank): homedepot.com
Milwaukee Tool, 10-pc SHOCKWAVE Impact Duty Carbide Hammer Drill Bit Set 48-20-9058 (contents 1/8, 5/32, 3/16, 7/32, 1/4, 5/16, 3/8, 1/2 in, 1/4 in hex shank): milwaukeetool.com
Bosch Professional, Fast Spiral Rotary Masonry Drill Bits BM5202 (published sizes 1/8 through 1 in): boschtools.com
Bosch Power Tools, Accessories Drilling Overview catalog PDF (masonry and concrete bit diameter ranges, individual bits to 1 in x 13 in): bosch-pt.com
Bridge Fasteners, Difference Between SDS, SDS-Plus and SDS-Max Drills (SDS-Plus 10 mm shank, 4 to 30 mm bits; SDS-Max 18 mm shank, 13 to 44 mm bits): bridgefasteners.com
GTSE, SDS Drill Bits Explained: Types and Sizes (10 mm SDS-Plus shank, typical 4 to 25 mm; 18 mm SDS-Max shank, heavier range; non-interchangeability): gtse.co.uk
Concrete Fastening Systems (Confast), Tapcon Installation (straight-shank bits fit 3/8 in or 1/2 in Jacobs-style chucks): confast.com
Home Depot, Milwaukee SHOCKWAVE Carbide Multi-Material Drill Bits category listing (1/8 to 5/16 in hex-shank carbide bits): homedepot.com
Concrete Fasteners, How Do I Determine the Size of Bit Needed for My Tapcon Screw (ANSI B212.15-1994 carbide bit, hammer mode): concretefasteners.com
Tapcon (ITW), official installation instructions for 3/16 in and 1/4 in diameters (bit pairings, hole 1/4 in deeper than embedment): tapcon.ca
ITW Red Head, Tapcon Anchors Product Data PDF (3/16 in anchors require 5/32 in bits, 1/4 in anchors require 3/16 in bits): buildsite.com
Concrete Fastening Systems (Confast), Installing Tapcon Concrete Screws (large-diameter pairings): confast.com
ToolsWeek, What Size Drill Bit for 3/16 Tapcon (ANSI B212.15-1994, 5/32 in carbide bit, hammer plus rotation): toolsweek.com
Confast, Installing Tapcon Concrete Screws (1 in minimum embedment, 1-3/4 in maximum, hole cleaning): confast.com