1. Identify the anchor family: concrete screw, heavy-duty screw anchor, wedge, sleeve, drop-in or adhesive.
2. Identify the exact product and its nominal size from the package or catalog.
3. Read the required nominal carbide bit for that product.
4. Confirm the hole depth, cleaning method and tool in the manufacturer’s instructions.
5. Check the fixture hole separately, because it is a different dimension.

If a product is not in the chart, do not borrow a value from a similar-looking anchor. Use that product’s own technical data.

The honest answer is “it depends on the anchor type.” Verified wedge anchors, heavy-duty screw anchors and sleeve anchors in the chart use a bit equal to the nominal anchor diameter. Small concrete screws use a smaller bit. Drop-in anchors use a larger bit than their size designation, and adhesive anchors use a hole larger than the rod.

Mechanical anchors are qualified for structural use under ACI CODE-355.2, and adhesive anchors are qualified separately under ACI 355.4, so the two should never be collapsed into one table.

The bit is smaller than the screw so the threads can cut into the sides of the hole and hold. Tapcon instructions call for a hammer drill and a hole 1/4 in. deeper than the anchor embedment, with a minimum embedment of 1 in. for these two sizes, then cleaning with a blow-out bulb or compressed air. These are Tapcon relationships and do not apply to every concrete-screw maker. Other Tapcon series (such as stainless or larger diameters) have their own bit sizes, so check the exact package. For full screw-anchor sizing, see the concrete screw sizes; for pilot holes in other materials, see the pilot hole size.

Simpson’s Titen HD heavy-duty screw anchor calls for a carbide drill bit the same diameter as the nominal diameter of the anchor, for its 1/4, 3/8, 1/2, 5/8 and 3/4 in. sizes, with minimum hole depths that vary with the chosen embedment. Titen HD is listed for cracked and uncracked concrete and masonry. “Concrete screw” alone is therefore not enough to choose a bit: you need the exact screw system and nominal diameter.

For Strong-Bolt 2, Simpson specifies a carbide-tipped bit complying with ANSI B212.15, matching the nominal anchor diameter, drilled with a rotary hammer to the specified nominal embedment depth. Embedment, length, torque, spacing and capacity are product-specific and covered in the wedge anchor sizes page.

Simpson specifies a carbide bit the same diameter as the nominal diameter of the Sleeve-All, drilled to the specified embedment depth and blown clean. ITW Red Head’s Dynabolt sleeve anchor likewise specifies a hole equal to the anchor diameter, drilled deeper than the minimum embedment, with ANSI B212.15 carbide bits. A sleeve anchor works differently from a wedge anchor, concrete screw or drop-in, so do not infer its drill size from another expansion anchor; read your product’s table.

A drop-in anchor is an internally threaded expansion anchor. The thread size is not automatically the hole size: a 1/2 in. drop-in needs a 5/8 in. bit in Simpson’s table, not a 1/2 in. bit. Installation generally means drilling the specified diameter and depth, cleaning the hole, inserting the anchor, expanding it with the specified setting tool, then installing the threaded rod or bolt. Simpson notes overhead installations need not be blown clean. Other makers’ drop-in anchors can differ, so follow the exact product table. Thread terminology is covered in the thread size chart and UNC thread sizes, and tap drill sizes apply to cutting threads in metal, not to anchor holes (see the tap drill chart).

ACI 355.4 addresses qualification of post-installed adhesive anchors in concrete. Adhesive systems may anchor threaded rod, reinforcing bar or internally threaded inserts, and the hole diameter is set by the exact rod or bar diameter, the adhesive system, the installation method and the evaluation report. The hole must be larger than the rod to leave room for adhesive: for Simpson’s SET-3G, the drill bit diameter ranges from 1/16 to 1/8 in. larger than the nominal anchor diameter, depending on the rod and conditions. Do not build one generic rod-to-bit table by mixing adhesive manufacturers.

For some evaluated systems d_a = d_b. For others d_b < d_a (small concrete screws), or d_b > d_a (drop-in anchors, adhesive rod systems). The drilled hole d₀ is whatever the exact product specifies. For nominal fastener sizes in general, see the bolt diameter chart.

A steel plate has a fixture clearance hole d_f, usually larger than the anchor. The concrete needs a drilled hole d_b set by the anchor system. For example, a 1/2 in. wedge anchor may use a 1/2 in. concrete bit while the base plate needs a larger clearance hole. The exact fixture-hole size belongs to the structural detailing. For steel holes see the bolt hole sizes and the clearance hole sizes; neither should be used to drill concrete.

For structural mechanical anchors, the drill bit itself can be part of the evaluated installation. Simpson’s Strong-Bolt 2 instructions call for a carbide-tipped bit that complies with ANSI B212.15, and ITW’s Tapcon and Dynabolt literature also reference it. The standard governs the bit’s carbide tip and its diameter requirements, which affect the drilled hole’s real size. A worn, damaged or incorrectly sized bit can change the actual hole geometry even when the printed bit size looks right. This page does not reproduce tolerance tables from the standard.

Concrete Anchor Hole Cleaning

Drilling the right diameter is only part of the job.

Hole preparation varies by system and can involve compressed air, brushing, vacuum drilling, blow-brush-blow sequences or manufacturer-approved alternatives. Tapcon instructions use a blow-out bulb or compressed air; Simpson’s Drop-In instructions call for compressed air, with overhead installations not needing to be blown clean. Cleaning matters most for adhesive anchors. Do not assume vacuum drilling is automatically acceptable, and do not apply one universal sequence to every anchor; follow the exact instructions for your anchor.

Oversized and Undersized Anchor Holes

Both can ruin an installation.

Oversized Holes

An oversized hole can prevent a mechanical anchor from engaging the concrete properly: improper expansion, inadequate thread engagement, reduced holding performance, a spinning anchor or installation failure. For structural applications, do not “fix” an oversized hole by installing a larger anchor unless the revised anchorage is specifically designed and permitted.

Undersized Holes

An undersized hole can keep the anchor from being inserted, require excessive driving force, damage the anchor or the concrete, cause improper thread formation or stop the evaluated installation from being achieved. Do not enlarge the hole randomly with an unsuitable bit.

Holes That Are Too Shallow or Too Deep

Too shallow, and the anchor may bottom out, miss the required embedment or be blocked by debris. Excess depth may be fine for some systems but should not be assumed acceptable. Follow the exact installation instructions.

Concrete Strength and Anchor Installation

Concrete properties do not change the bit size.

The bit dimension comes from the anchor system. Concrete strength affects the anchor’s qualified performance and tabulated values, not a user-adjusted bit size. For background on strength, see the concrete PSI.

TOOLS & EQUIPMENT

Equipment for Your Project

AMAZON TOOLS DEWALT DW1361 21-Piece Drill Bit SetGeneral-purpose drill bits for suitable materialsExplore tools ↗ AMAZON TOOLS Mitutoyo 500-196-32 Digital CaliperPrecision measurements of material and fastener dimensionsExplore tools ↗

Affiliate disclosure: As an Amazon Associate, ConcreteCalculate earns from qualifying purchases. We may also earn a commission from other affiliate links at no additional cost to you.

Cracked vs. Uncracked Concrete

Correct bit size is necessary but not sufficient.

ACI CODE-355.2 sets qualification criteria for mechanical anchors for uncracked concrete only, or for cracked and uncracked concrete, depending on the anchor. Drill-bit size alone tells you almost nothing about structural suitability. A correct bit is one necessary part of a compliant anchor installation, along with the right anchor, embedment, spacing, edge distance and member thickness.

Concrete vs. Block vs. Brick

Not interchangeable base materials.

Normal-weight concrete, lightweight concrete, grout-filled CMU, hollow CMU, brick and stone are different base materials. An anchor qualified for concrete is not automatically qualified for masonry, and many people call every masonry fastener a “concrete anchor.” Some products, such as the Titen HD, are listed for both concrete and masonry, but check the product report for the exact base material before drilling.

What to Do if You Hit Rebar

Stop, and do not improvise.

If the bit hits reinforcement, stop drilling. Do not cut or damage rebar without engineering authorization, and do not enlarge the hole or switch to a different anchor on the spot. Contact the engineer of record: relocating an anchor means rechecking edge distance, spacing and member thickness. Abandoned holes also affect nearby anchors. For rebar cover context, see the concrete cover chart.

Common Concrete Anchor Drilling Mistakes

Quick checks before you drill.

🎯

Selecting the bit from diameter without the anchor type

Type comes first.

📏

Assuming every 1/4 in. anchor uses a 1/4 in. bit

Tapcon uses 3/16 in.

🧰

Assuming every concrete screw uses a smaller pilot

Titen HD uses a matching bit.

🔧

Assuming every heavy-duty screw uses the Tapcon relationship

Check the product.

🏭

Assuming every wedge system is identical

Verify each product.

🔄

Mixing drill data from different manufacturers

Never combine them.

⚠️

Using a wedge-anchor table for sleeve anchors

Different systems.

🚫

Using a wedge-anchor table for drop-ins

Drop-ins use larger bits.

🧹

Using a mechanical table for adhesive anchors

Adhesives need a larger hole.

🔩

Confusing rod diameter with adhesive hole diameter

The hole is larger.

🧱

Confusing drop-in thread size with hole size

Use the product table.

🕓

Confusing the fixture hole with the concrete hole

They are different.

📑

Using the Bolt Hole Size Chart to drill concrete

It is for steel.

📝

Using the Clearance Hole Size Chart to drill concrete

It is for fixtures.

📐

Confusing bit diameter with hole depth

Different dimensions.

⛏️

Confusing hole depth with nominal embedment

They are not equal.

🔄

Confusing nominal with effective embedment

Design uses effective.

🔗

Assuming overall anchor length equals drill depth

Length includes hardware.

🧾

Ignoring fixture thickness

It adds to length.

⚠️

Using a worn carbide bit

It drills an undersized hole.

💥

Using a damaged bit

It changes hole geometry.

❌

Using the wrong bit type

Use the specified bit.

📜

Ignoring ANSI B212.15 where required

Evaluated anchors may require it.

📐

Drilling at an excessive angle

Drill perpendicular.

🌀

Letting the bit wander

It oversizes the hole.

⏱️

Failing to drill to required depth

The anchor may bottom out.

🧹

Failing to account for debris

Leave dust space where allowed.

🧹

Failing to clean the hole

Cleaning can be required.

🚫

Using an unapproved cleaning method

Follow the instructions.

💨

Assuming vacuum drilling is always acceptable

Check the product.

⚪

Installing in an oversized hole

It reduces holding.

🔨

Forcing an anchor into an undersized hole

It can damage the anchor.

🔄

Re-drilling randomly to fix a bad hole

Ask the engineer.

🧭

Moving an anchor without rechecking edge distance

Spacing changes too.

🧱

Ignoring reinforcement

Locate rebar first.

⚠️

Damaging rebar without authorization

Contact the engineer.

🧱

Assuming concrete qualification includes brick

It does not.

🧱

Assuming concrete qualification includes hollow block

It does not.

⚡

Ignoring cracked-concrete requirements

Check qualification.

🌋

Ignoring seismic qualification

It is product-specific.

🧱

Ignoring concrete strength

It affects performance.

📐

Ignoring minimum member thickness

It limits embedment.

📙

Ignoring edge distance

Edge breakout risk.

🔗

Ignoring anchor spacing

Breakout zones overlap.

🌐

Using a generic internet chart

Use the exact instructions.

Concrete Anchor Drill Bit FAQs

Thirty-six common questions, answered by anchor type.

What size drill bit do I need for concrete anchors?

It depends on the anchor type and product. A 1/4 in. Tapcon uses a 3/16 in. bit, a 1/4 in. Simpson Titen HD uses a 1/4 in. bit, and drop-in and adhesive anchors use larger holes. Always follow the exact manufacturer’s installation data.

Is the drill bit the same size as the concrete anchor?

Sometimes. Evaluated wedge anchors such as Simpson Strong-Bolt 2, heavy-duty screw anchors such as Titen HD and sleeve anchors such as Simpson Sleeve-All use a bit equal to the nominal anchor diameter. Small concrete screws use a smaller bit, and drop-in and adhesive anchors use a larger one.

What size bit for a 3/16-inch Tapcon?

A 5/32 in. bit, per ITW Tapcon instructions.

What size bit for a 1/4-inch Tapcon?

A 3/16 in. carbide bit, per ITW Tapcon instructions. Not a 1/4 in. bit, even though the package may say 1/4 in.

What size drill bit for a 1/4-inch concrete anchor?

The anchor type is required. A 1/4 in. Tapcon uses a 3/16 in. bit; a 1/4 in. Simpson Titen HD, a 1/4 in. Strong-Bolt 2 wedge anchor or a 1/4 in. Sleeve-All uses a 1/4 in. bit; a 1/4 in. Simpson Drop-In uses a 3/8 in. bit.

What size bit for a 3/8-inch wedge anchor?

A 3/8 in. nominal carbide bit for the evaluated wedge-anchor systems researched, such as Simpson Strong-Bolt 2. Verify the exact product.

What size bit for a 1/2-inch wedge anchor?

A 1/2 in. nominal carbide bit for the evaluated systems researched, such as Strong-Bolt 2. Confirm your product’s instructions.

What size bit for a 5/8-inch wedge anchor?

A 5/8 in. nominal carbide bit for the evaluated systems researched, such as Strong-Bolt 2.

What size bit for a 3/4-inch wedge anchor?

A 3/4 in. nominal carbide bit for the evaluated systems researched, such as Strong-Bolt 2.

What size drill bit for a Titen HD?

Simpson specifies a carbide bit the same diameter as the nominal anchor diameter: 1/4, 3/8, 1/2, 5/8 or 3/4 in. for those sizes.

What size drill bit for a sleeve anchor?

For Simpson Sleeve-All, a carbide bit the same diameter as the nominal anchor diameter. ITW Red Head Dynabolt sleeve anchors also specify a hole equal to the anchor diameter. Check your product’s table.

What size bit for a 1/2-inch sleeve anchor?

A 1/2 in. carbide bit for Simpson Sleeve-All and for ITW Red Head Dynabolt. Confirm your exact product.

What size drill bit for a drop-in anchor?

It is product-specific and not the same as the size designation. In Simpson’s Drop-In table, the 1/4 in. size uses a 3/8 in. bit, the 3/8 in. size a 1/2 in. bit and the 1/2 in. size a 5/8 in. bit.

What size drill bit for a 1/2-inch drop-in anchor?

For Simpson’s 1/2 in. Drop-In, a 5/8 in. carbide bit. Other manufacturers can differ, so use the exact product table.

What bit for a 1/2-inch threaded rod with epoxy?

It depends on the adhesive system. The hole must be larger than the rod, and for Simpson’s SET-3G the bit is 1/16 to 1/8 in. larger than the nominal anchor diameter depending on the rod and conditions. Use the exact adhesive’s table.

How deep do I drill for a concrete anchor?

There is no universal depth. It depends on the anchor system, nominal and effective embedment and the installation method. Follow the current manufacturer instructions or evaluation report.

How much deeper should the hole be than the anchor?

It depends on the product. Tapcon instructions call for 1/4 in. deeper than the embedment, while other products specify a different depth or a fixed-depth bit. Do not universalize one rule.

Is hole depth the same as embedment?

No. Hole depth h0 is generally at least the nominal embedment hnom, and the relationship is system-specific.

What is effective embedment?

The effective anchorage depth used in structural design, listed separately from nominal embedment in the product’s evaluation report or design data.

Do I need a carbide drill bit?

For concrete anchors, yes: the evaluated systems cited specify carbide-tipped bits, typically meeting ANSI B212.15.

What is an ANSI B212.15 bit?

A carbide-tipped masonry bit made to the ANSI B212.15 dimensional requirements. Simpson’s Strong-Bolt 2 instructions call for a bit complying with it.

Can I use a regular drill?

No. Concrete anchor installations call for a carbide-tipped bit in a hammer drill or rotary hammer, as the product’s instructions specify.

Do I need a hammer drill?

Often yes. Tapcon instructions, for example, call for a hammer drill. The manufacturer’s instructions control the permitted method.

Do I need a rotary hammer?

For some anchors and larger or deeper holes. Simpson’s Strong-Bolt 2 instructions call for a rotary hammer drill. Follow the instructions for your product.

Can I use an SDS bit?

SDS-plus and SDS-max describe the shank type used with rotary hammers. The bit must still have the right diameter, carbide tip and ANSI conformity the anchor requires.

How do I clean the hole?

Follow the anchor’s instructions. Tapcon uses a blow-out bulb or compressed air, Simpson Drop-In uses compressed air (not required overhead), and adhesive systems have specific brushing and blowing sequences.

What happens if my concrete hole is too big?

A mechanical anchor may not expand or engage properly, giving reduced holding performance, a spinning anchor or installation failure. For structural applications, do not just install a larger anchor unless it is designed and permitted.

What if the hole is too small?

The anchor may not insert, may need excessive force and may be damaged or fail to install as evaluated. Do not enlarge it randomly with an unsuitable bit.

Can I drill deeper than required?

Only if the product allows it. Some systems allow or suggest extra depth for dust space, but do not assume it is acceptable for every anchor.

Can I reuse an anchor hole?

Not casually. A used or abandoned hole can affect edge distance and spacing for nearby anchors, so ask the engineer of record or the manufacturer before reusing or moving an anchor.

Can I use the same bit for concrete and brick?

Do not assume so. Concrete, brick and block are different base materials, and the anchor and its bit must be approved for the one you are drilling.

Can I drill through rebar?

Not without engineering authorization. Do not cut or damage reinforcement on your own.

What happens if I hit rebar?

Stop drilling and contact the engineer of record. Relocating an anchor requires rechecking edge distance, spacing and member thickness.

Can concrete anchors be installed in block?

Only if the specific anchor is qualified for that block type. Concrete qualification does not imply masonry qualification, and hollow and grout-filled CMU differ.

Can wedge anchors be installed in brick?

Do not assume so. Wedge anchors are qualified for specific base materials, and brick is generally not covered by concrete qualification. Use only a product whose instructions allow it.

Does concrete PSI change the drill-bit size?

No. The bit dimension comes from the anchor system. Concrete properties influence qualification and performance, not a user-adjusted bit size.

Standards and References Used

Primary sources behind the information on this page

Reference	What It Covers	Used For
ACI CODE-355.2-24	Qualification of post-installed mechanical anchors	Mechanical anchor qualification
ACI 355.4	Qualification of post-installed adhesive anchors in concrete	Adhesive anchor context
ITW Tapcon installation instructions (3/16 and 1/4)	Tapcon bit sizes, hole depth, cleaning	Concrete screw bits
Simpson Titen HD	Heavy-duty screw anchor product data	Titen HD bit sizes
Simpson Strong-Bolt 2 anchor anatomy	Wedge anchor installation, ANSI B212.15 bit	Wedge anchor bits
Simpson Drop-In fixed-depth drill bits	Drop-In anchor bit diameters and depths	Drop-in bits
ITW Red Head Dynabolt sleeve anchors	Sleeve anchor hole and depth guidance	Sleeve anchor hole sizing

All numerical product values are specific to the named product. Manufacturer instructions and ICC-ES evaluation reports govern. Local codes, project drawings and the engineer of record govern structural anchorage.

Related Charts

📊Wedge Anchor Size Chart📊Concrete Screw Size Chart📊Drill Bit Size Chart📊Pilot Hole Size Chart📊Bolt Hole Size Chart📊Clearance Hole Size Chart📊Anchor Bolt Size Chart📊Anchor Bolt Spacing Chart📊Bolt Diameter Chart📊Thread Size Chart📊UNC Thread Chart📊Tap Drill Chart📊Nut Size Chart📊Washer Size Chart📊Concrete PSI Chart📊Concrete Cover Chart📊Footing Size Chart📚Browse All Construction Charts

Related Calculators

These tools are aimed at cast-in-place and foundation anchorage, not post-installed anchor drilling data. Use the anchor manufacturer’s data for the drill bit and hole.

🧮Bolt Pattern Calculator🧮Anchor Bolt Calculator🧮Anchor Bolt Embedment Calculator

📥 Download Concrete Anchor Drill Bit Chart PDF

Use your browser’s print function to save this page as a PDF for jobsite binders, estimating folders and reference.

Print-Ready Letter FormatVerified Bit RelationshipsHole Depth vs. EmbedmentFractional Bit ConversionsInstant Browser PDF

🖨️ Save / Print as PDF

🔗 Cite or Embed This Chart

Feel free to reference this chart on your own site or article. Copy the citation below and link back to this page.

<p>Concrete Anchor Drill Bit Size Chart via <a href=”https://concretecalculate.com/concrete-anchor-drill-bit-size-chart/”>ConcreteCalculate.com</a></p>

📋 Copy Embed Code