Masonry Drill Bit Selection Guide

Masonry drill bits look similar on the outside, but the wrong type for your application will cost you time, bits, or both. Anchor-setting bits are not the same as general masonry bits. Bits designed for hammer drilling will fail in rotary-only use. And if you hit rebar mid-hole, there is a specific tool for that too. This guide covers every type of masonry drill bit we stock, what each one is designed for, and how to choose the right one for your job.

In This Guide:

• Bit Type Overview
• SDS+ Anchor-Setting Bits
• General Purpose Masonry Bits
• Tapcon / Screw Anchor Pilot Bits
• Rebar Eater Bits
• A-Taper & Spline Shank Bits
• Anchor-to-Bit Size Chart
• Frequently Asked Questions

Masonry Drill Bit Types at a Glance

All of the bits below are carbide-tipped and made in the USA by Relton. The main differences are shank type (how the bit connects to the drill), application (what task it is designed for), and drill operation (whether the bit works with hammer action or rotary only).

SDS+ Anchor-Setting Bits (REL207 Series)

The REL207 is the bit to reach for when you are installing wedge anchors, sleeve anchors, or any expansion anchor that requires an exact-diameter hole. These bits are manufactured to ANSI B212.15 tolerance, which means the hole diameter is controlled to the precision required for proper anchor expansion. A hole drilled oversize — even by a few thousandths — can reduce anchor pull-out strength by 20% or more.

The SDS+ shank locks into the chuck on any SDS-Plus rotary hammer without a key and transfers energy efficiently to the carbide tip. Available in diameters from 3/16" through 1" and OAL options from 4" up to 18" for deep embedment applications.

General Purpose Masonry Bits (GRT, R4X, Tip-Top)

Not every hole in concrete needs ANSI-tolerance precision. For through-holes, conduit penetrations, lag shield pilots, and general masonry work, the Groo-V Tip (RELGRT) and R4X (RELRX) round-shank bits are workhorses that run in any standard hammer drill or rotary hammer. They accept the same drill chuck as a standard twist bit, so no adapter needed.

Groo-V Tip (RELGRT): Named for its aggressive V-groove carbide tip that clears chips efficiently. Available 1/8" through 1" in OAL from 3" to 8". Good all-around performer in concrete, block, and brick.

R4X (RELRX): Four-cutter tip design for faster chip removal in harder concrete. Sizes 3/16" through 1", with 6" and 12" OAL options for deeper work. Preferred for high-cycle production drilling.

Tip-Top (RELTT): Rotary-only bit for work where hammer vibration is not acceptable — tile, glazed block, decorative brick, or materials that crack under percussion. Run at higher RPM in rotary mode only.

Tapcon & Concrete Screw Anchor Pilot Bits (RELTC)

Concrete screw anchors (Tapcon, Titen HD, and similar self-tapping anchors) require a pilot hole that is slightly smaller than the anchor diameter. The threads of the screw cut into the concrete wall of the pilot hole to create their hold. If the pilot hole is the wrong size — even a bit too large — the threads will not engage and the anchor will spin out.

The RELTC series is sized specifically for the two most common Tapcon-style anchor diameters:

• 3/16" screw anchor → use a 5/32" pilot bit (RELTC-5 series)
• 1/4" screw anchor → use a 3/16" pilot bit (RELTC-3 series)

Available in 3-1/2", 4-1/2", and 5-1/2" OAL to match the embedment depth of your anchor. Do not substitute a standard masonry bit — the diameter tolerance is too loose and will produce an oversized pilot hole.

Rebar Eater Bits (RELRB & RELSRB)

How it works: Switch your rotary hammer to rotation-only mode. Insert the Rebar Eater and let it cut through the steel at moderate speed. You will feel the resistance drop when you break through. Switch back to hammer mode, swap back to your standard anchor-setting bit, and finish the hole in concrete.

Sizes: Available in diameters from 3/8" through 2-1/2", in both straight shank (RELRB — use with any drill) and SDS+ shank (RELSRB — stays in the rotary hammer chuck, no tool swap required). For rebar up through 13/16", the bit is a 1-piece cutter. For 7/8" and larger, Relton uses a 2-piece cutter design for better chip clearance.

A-Taper & Spline Shank Bits

Before SDS+ became the industry standard, rotary hammers used two other chuck systems: A-taper and spline drive. If you are working with older equipment, these are still the right bit for the job.

A-Taper (RELA): A tapered hex shank used on older Hilti, Bosch, and other European rotary hammers. If your drill chuck requires a key and the bit shank is tapered with a flat, you have an A-taper drill. Available in 3/16" through 7/8".

Spline (REL202): A multi-fluted shank common on older large-diameter Bosch rotary hammers. Provides higher torque transfer than SDS+ and is still used on some commercial rotary hammers for 3/4" and larger bits. If you have an SDS-Max drill and need to use SDS+ bits, a Quik-Lok adapter (RELQL-MX) handles that conversion.

Anchor-to-Bit Size Chart

Use this table to find the correct bit for any standard concrete anchor application. For wedge and sleeve anchors, the bit diameter matches the anchor diameter exactly. For screw anchors, use the pilot bit size listed below.

Frequently Asked Questions

What is the difference between an SDS+ and a standard round shank masonry bit?

An SDS+ bit has a specially shaped shank with two open grooves and two locking slots. It locks into an SDS+ chuck without a key and can slide slightly during hammering, which makes energy transfer more efficient. A round shank bit requires a keyed or keyless chuck and does not slide — all the hammer impact goes through the chuck instead of directly into the bit. SDS+ is faster, more efficient, and causes less wear on the drill for heavy concrete work. Round shank bits work fine in standard hammer drills for light-duty use.

Can I use an SDS+ masonry bit in a standard drill?

Not directly. An SDS+ bit will not fit in a standard drill chuck. You would need an SDS+ to round shank adapter, which defeats most of the efficiency advantage. If you have a standard drill, use a round shank masonry bit (RELGRT or RELRX). If you are buying a drill for regular concrete work, an SDS+ rotary hammer is worth the investment.

Why does my anchor pull out even though I used the right bit size?

The most common causes are: hole not blown out before installing the anchor (dust at the bottom prevents full embedment), hole not drilled deep enough, anchor not driven to the correct embedment depth, or concrete that is weaker or thinner than the anchor requires. Check the minimum concrete thickness in our drill bit chart for your anchor size.

What size masonry bit do I need for a 1/2 inch wedge anchor?

A 1/2" wedge anchor requires a 1/2" drill bit. Use the Relton REL207-8 series SDS+ bit for the cleanest, most precisely sized hole. The -6 OAL (4" usable depth) is the most common choice for standard embedment. Use the -10, -14, or -18 OAL for deeper embedment requirements. Browse 1/2" SDS+ bits →

Do Rebar Eater bits work in any drill?

The straight shank Rebar Eater (RELRB) works in any drill with a standard keyless or keyed chuck. The SDS+ version (RELSRB) requires an SDS+ rotary hammer. Both must run in rotary-only mode — do not use hammer action when cutting rebar. After cutting through the rebar, switch back to hammer mode to finish the concrete hole with your standard masonry bit.

How do I know if I need an A-taper or spline bit vs. SDS+?

Look at your drill’s chuck. SDS+ chucks have a smooth round opening with a spring-loaded ball visible inside. A-taper chucks look like a keyed or keyless drill chuck but are tapered and slightly larger. Spline chucks have internal flutes visible inside the opening. Most rotary hammers sold after 2000 use SDS+. If you have an older tool and are not sure, bring it in or send us a photo — contact us and we can confirm the right bit.

Related Resources

• Concrete Anchor Drill Bit & Hole Size Chart — drill bit diameter, hole depth, and torque specs by anchor size
• Wedge Anchor Installation Guide — step-by-step installation, torque tables, material selection
• Sleeve Anchor Installation Guide — installation steps, load data, CMU applications
• Concrete Anchor Selection Guide — choosing the right anchor type for your application
• Shop SDS+ Anchor-Setting Bits
• Shop Rebar Eater Bits
• Shop All Masonry Drill Bits