Use a 3/16-Inch Masonry Bit for a 1/4-Inch Tapcon

For a 1/4-inch-diameter Tapcon concrete screw, use a 3/16-inch-diameter masonry drill bit—not a 1/4-inch bit. Tapcon specifies this pairing in its 3/16- and 1/4-inch anchor installation guide.

The required bit diameter is 0.1875 in., or approximately 4.76 mm. That metric figure is a conversion, not approval to substitute a nearby metric bit.

Quick size chart

These sizes apply to the small-diameter Tapcon anchors covered by the manufacturer’s guide. Do not carry the pairing over to another brand or anchor type without checking its instructions.

Which bit should you buy?

Choose a 3/16-inch carbide-tipped Tapcon masonry bit with a shank compatible with your drill. Tapcon offers standard bits and SDS bits; its SDS version is intended for rotary hammer drills. The manufacturer specifies its system bits because they are made to tighter tolerances than standard ANSI bits. See the Tapcon drill-bit specifications and installation guide.

Read both dimensions on the package: 3/16 × 4-1/2 in. identifies the bit’s diameter and length. The second number is not the required hole depth.

Hole depth and a worked example

Tapcon instructs installers to drill 1/4 in. deeper than the anchor embedment. Its selection chart lists embedment from 1 to 1-3/4 in., depending on screw length and fixture thickness. Embedment is the portion entering the masonry—not the screw’s full length. Source: Tapcon installation guide.

Example: A 1/4 × 1-3/4-inch hex-head Tapcon passing through a 1/2-inch-thick fixture seated directly against concrete gives:

• Embedment: 1-3/4 − 1/2 = 1-1/4 in.
• Hole depth into concrete: 1-1/4 + 1/4 = 1-1/2 in.
• Drill-bit diameter: 3/16 in.

If drilling through the fixture, allow for its thickness when setting the drill’s depth stop.

The manufacturer’s sequence is: drill with the hammer function on, remove dust using a blow-out bulb or compressed air, then drive the screw until fully seated with the hammer function off. Follow the complete installation instructions.

The example checks dimensions only; it does not establish load capacity. For structural or safety-critical attachments, verify the exact anchor’s approval, substrate, spacing and edge-distance requirements against the project design and local code.