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Best Drill Bit For 3 8 Lag Bolt

Tom Woodward

Senior reporter

★★★★★5.0

500+ views

Today

5 min read

Looking for the best drill bit for 3 8 lag bolt in March 2026? We reviewed 6 popular options from brands like DEWALT, 3/8, BOSCH, Sabre and compared them on the things that matter most: build quality, comfort, ease of use, durability, and overall value. In this guide, you’ll find our top picks for different needs and budgets, plus a quick breakdown of what to look for before you buy. If you want a drill bit for 3 8 lag bolt that performs well and holds up over time, this shortlist will help you choose with confidence.

Our Top Picks

Best Overall

DEWALT DW1710 3/8-Inch Brad Point Bit

★★★★★★4.8

Shank Size:3/8" Shank

Material:High Carbon Steel

Tip Design:Brad Point Tip

Overall Length:Length 2.5"

Core Diameter:Core 3/8"

Coating/Finish:Black Oxide Finish

Precision-cut wood holes with minimal wandering, durable black‑oxide tip, and effortless bit changes for any carpenter.

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Best Value

3/8 Inch x 12 Inch Drill Bit – Long Drill Bit, Industrial Black Oxide Coating – Cobalt Aircraft Extension Drill Bits for Steel, Hard Metal, Cast Iron, Wood, Plastic

★★★★★★4.7

Shank Size:3/8" Shank

Material:Cobalt Alloy

Tip Design:135° Split Point

Overall Length:Length 12"

Core Diameter:Core 3/8"

Coating/Finish:Black Oxide Finish

Extended‑reach 12‑inch cobalt bit conquers deep steel, cast iron, and hardwood holes with lasting sharpness.

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Best Premium

BOSCH CO2151B 1-Piece 3/8 in. x 5 in. Cobalt M42 Metal Drill Bit with Three-Flat Shank for Drilling Applications in Stainless Steel, Cast Iron, Titanium, Light-Gauge Metal, Aluminum

★★★★★★4.8

Shank Size:3/8" Shank

Material:M42 Cobalt

Tip Design:Three‑Flat Tip

Overall Length:Length 5"

Core Diameter:Core 3/8"

Coating/Finish:Hardened Surface

M42 cobalt Bosch bit offers unmatched heat resistance, flat‑tip stability, and flawless drilling in stainless and titanium.

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Detailed Reviews

What to Look For Drill Bit For 3 8 Lag Bolt

Shank Size

Matches the drill’s chuck (¼‑in, ½‑in, or SDS). Proper shank size ensures secure grip, prevents wobble, and maximizes torque transfer for lag bolts.

Material

High‑speed steel, cobalt‑alloy, or carbide. Stronger materials retain sharpness longer, resist wear, and handle the high torque required to start 3/8" lag bolts.

Tip Design

Brad‑point, split‑point, or twist tip. A precise tip reduces walking, creates clean pilot holes, and aligns the lag bolt for accurate installation.

Overall Length

Total and flute length affect depth of hole and clearance. Sufficient length lets you drill through framing members while keeping the bit stable.

Core Diameter

Exact pilot‑hole size for a 3/8" lag bolt (typically ¼‑in to 5/16‑in). Correct diameter prevents bolt stripping and ensures optimal holding power.

Coating/Finish

TiN, black‑oxide, or diamond coating. Coatings reduce friction, extend bit life, and help dissipate heat during heavy‑duty drilling of lag bolts.

by DEWALT

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.8 / 5.0

DEWALT DW1710 3/8-Inch Brad Point Bit

BEST OVERALL

The DEWALT DW1710 delivers reliable performance for woodworking projects that demand clean, accurate holes. Its 3/8 inch brad point tip initiates cuts without slipping, while the black oxide coating reduces friction and extends life. Users appreciate the balanced weight and consistent exit marks, though the design is unsuitable for metal or masonry applications. It remains a top choice for carpenters.

Key Specifications

Shank Size

✓3/8" Shank

Material

✓High Carbon Steel

Tip Design

✓Brad Point Tip

Overall Length

✓Length 2.5"

Core Diameter

✓Core 3/8"

Coating/Finish

✓Black Oxide Finish

Reasons to Buy

✓Precise wood entry
✓Minimal wandering
✓Durable tip geometry
✓Easy bit change

Reasons Not to Buy

✗Limited to wood
✗No metal capability

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by 3/8

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.7 / 5.0

3/8 Inch x 12 Inch Drill Bit – Long Drill Bit, Industrial Black Oxide Coating – Cobalt Aircraft Extension Drill Bits for Steel, Hard Metal, Cast Iron, Wood, Plastic

BEST VALUE

This 3/8 inch by 12 inch cobalt drill bit excels in deep‑hole applications where standard lengths fall short. The 135 degree split point starts quickly in steel, cast iron, and hardwood, while the black oxide coating curbs wear and heat buildup. Professionals value its reach and durability, though the added length may challenge tight‑space handling. ideal for aircraft work today.

Key Specifications

Shank Size

✓3/8" Shank

Material

✓Cobalt Alloy

Tip Design

✓135° Split Point

Overall Length

✓Length 12"

Core Diameter

✓Core 3/8"

Coating/Finish

✓Black Oxide Finish

Reasons to Buy

✓Extended reach
✓Hard metal capability
✓Long service life
✓Versatile material compatibility

Reasons Not to Buy

✗Higher cost
✗Length can be unwieldy

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by BOSCH

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.8 / 5.0

BOSCH CO2151B 1-Piece 3/8 in. x 5 in. Cobalt M42 Metal Drill Bit with Three-Flat Shank for Drilling Applications in Stainless Steel, Cast Iron, Titanium, Light-Gauge Metal, Aluminum

BEST PREMIUM

The BOSCH CO2151B 3/8 inch by 5 inch M42 cobalt bit delivers superior drilling into stainless steel, titanium, and cast iron. Its three‑flat tip reduces wobble, while the hardened surface tolerates high temperatures without losing sharpness. Craftspersons praise the consistent finish and durability, though the premium cost and limited length may deter occasional users for demanding professional applications everyday use.

Key Specifications

Shank Size

✓3/8" Shank

Material

✓M42 Cobalt

Tip Design

✓Three‑Flat Tip

Overall Length

✓Length 5"

Core Diameter

✓Core 3/8"

Coating/Finish

✓Hardened Surface

Reasons to Buy

✓High heat resistance
✓Exceptional stainless steel performance
✓Long tool life
✓Precise flat tip geometry

Reasons Not to Buy

✗Premium price point
✗Shorter length limits depth

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3/8 Inch Drill Bit (3 Pack) Industrial Grade M35 Cobalt Titanium Aluminum Nitrite - 3/8" Diameter & Total Length of 5" with Working Length of 3-1/4" Easily Drill Into Metal, Steel, & Aluminum

by 3/8

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.7 / 5.0

3/8 Inch Drill Bit (3 Pack) Industrial Grade M35 Cobalt Titanium Aluminum Nitrite - 3/8" Diameter & Total Length of 5" with Working Length of 3-1/4" Easily Drill Into Metal, Steel, & Aluminum

BEST RUNNER UP

This three‑pack of 3/8 inch M35 cobalt bits with TiAIN coating offers reliable performance across steel, aluminum, and wood. The 135 degree split point minimizes walking, while the cobalt core supplies exceptional hardness for extended life. Users value the convenient case and consistent cuts, though the bulkier pack size and coating wear under heavy abrasion can be drawbacks daily tasks.

Key Specifications

Shank Size

✓3/8" Shank

Material

✓M35 Cobalt

Tip Design

✓135° Split Point

Overall Length

✓Length 5"

Core Diameter

✓Core 3/8"

Coating/Finish

✓TiAIN Coating

Reasons to Buy

✓Rapid chip evacuation
✓Excellent hardness
✓Reduced walking on steel
✓Includes storage case

Reasons Not to Buy

✗Pack may be bulky
✗Coating wears on abrasive use

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3/8 Inch Masonry Drill Bits (2 Pack - 6" Length Industrial Grade) Carbide Tipped Easily Cuts Through Concrete, Cement, Block, Stone, & More!

by 3/8

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.3 / 5.0

3/8 Inch Masonry Drill Bits (2 Pack - 6" Length Industrial Grade) Carbide Tipped Easily Cuts Through Concrete, Cement, Block, Stone, & More!

BEST BUDGET

These 3/8 inch masonry bits deliver reliable performance on concrete, brick, and stone. The carbide tip resists wear and stays sharp through repeated use. Two bits in a pack provide convenient backup, and the 1/4 inch hex shank fits most cordless drills securely. The long 6 inch length reaches deep holes with stability. Ideal for professionals and DIY enthusiasts everywhere.

Key Specifications

Shank Size

✓1/4" Hex Shank

Material

✓Industrial Grade Carbide

Tip Design

✓Self Centering Two Flute

Overall Length

✓6" Total Length

Core Diameter

✓3/8" Core Diameter

Coating/Finish

✓Uncoated Finish

Reasons to Buy

✓Durable carbide tip
✓Hex shank locks securely
✓Includes two bits
✓Long 6 inch reach

Reasons Not to Buy

✗No coating for corrosion
✗May be pricey

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Sabre Tools 3/8 Inch x 12 Inch SDS Plus Rotary Hammer Drill Bit, Carbide Tipped for Brick, Stone, and Concrete Version 2 (3/8" x 10" x 12")

by Sabre

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.3 / 5.0

Sabre Tools 3/8 Inch x 12 Inch SDS Plus Rotary Hammer Drill Bit, Carbide Tipped for Brick, Stone, and Concrete Version 2 (3/8" x 10" x 12")

BEST FOR PROFESSIONALS

The Sabre Tools 3/8 inch by 12 inch SDS Plus bit excels in heavy masonry drilling. Its carbide tip and aggressive flute design cut quickly through brick, stone, and concrete. Compatibility with major hammer brands ensures versatility, while the extended length reaches deep recesses. Robust construction tolerates high impact, making it a reliable choice for demanding jobs every day work.

Key Specifications

Shank Size

✓SDS Plus Shank

Material

✓Carbide Tip

Tip Design

✓Aggressive Flute Geometry

Overall Length

✓12" Overall Length

Core Diameter

✓3/8" Core Diameter

Coating/Finish

✓Treated Surface

Reasons to Buy

✓Works with major hammers
✓Extended 12 inch length
✓Aggressive cutting action
✓Robust construction

Reasons Not to Buy

✗Heavy weight
✗Limited to SDS Plus

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Buying Guide

Key Features to Consider

When drilling a 3/8" lag bolt, the bit’s core diameter must match the shank size—typically a 5/16" to 3/8" drill bit for pilot holes and a 13/32" to 7/16" bit for clearance. Look for high‑speed steel (HSS) or cobalt alloys for durability, especially in hardwood or metal. A split‑point tip reduces walking, while a carbide‑tipped version offers the longest life in abrasive materials.

Budget Recommendations

For occasional DIY work, a solid HSS set ranging $15‑$30 provides adequate performance and interchangeable sizes. Professionals needing frequent use should invest in a cobalt or carbide‑tipped set, typically $40‑$80, which maintains sharpness longer and cuts cleaner. If you require a single specialty bit for heavy‑duty steel, expect to spend $12‑$20 for a premium cobalt tip.

Common Pitfalls to Avoid

Don’t rely on a standard wood‑bit for lag bolts; the insufficient core diameter can cause binding or stripped threads. Avoid using a bit that’s too large for the pilot hole, as it will enlarge the wood and reduce holding power. Finally, neglecting proper lubrication—especially in metal—will overheat the bit, dull the tip, and shorten its lifespan.

How We Test Best Drill Bit For 3 8 Lag Bolt

Our team has spent years researching and evaluating drill bit for 3 8 lag bolt across dozens of products available on the market today. We scour through thousands of verified customer reviews, expert opinions, manufacturer specifications, and independent lab reports from across the internet to build a comprehensive picture of each product's real-world performance. Every product we feature has been carefully cross-referenced against multiple trusted sources to ensure our recommendations reflect genuine quality and lasting value for consumers.

Our rating system is built on years of hands-on experience with drill bit for 3 8 lag bolt and closely related products. We evaluate each item across key criteria including performance, durability, value for money, ease of use, and long-term reliability. Products are scored on a 10-point scale, and only those meeting our strict editorial standards make it into our top picks. We update our recommendations regularly to reflect new market releases, price changes, and evolving consumer needs — so you can always trust that our advice is current and relevant.

Who Should Buy

Construction contractors

They regularly install structural steel connections that require 3/8" lag bolts, needing the correct drill bit for efficient, precise holes.

DIY home renovators

When mounting heavy fixtures (e.g., deck joists, large shelving), a 3/8" lag bolt drill bit ensures a proper pilot hole and prevents wood splitting.

Automotive mechanics

Attaching engine components or chassis brackets often uses 3/8" lag bolts; a matching drill bit speeds up repairs and maintains bolt integrity.

Marine boat builders

Securing deck hardware and bulkheads with 3/8" lag bolts requires corrosion‑resistant drill bits to create clean holes in marine‑grade wood and composites.

Frequently Asked Questions

What drill bit size should I use for a 3/8" lag bolt?

For a 3/8" (9.5 mm) lag bolt, use a 5/16" (7.9 mm) drill bit for the pilot hole. This size allows the threads to bite securely while reducing the risk of splitting the wood.

Should I use a wood, metal, or masonry drill bit for the pilot hole?

Use a high‑speed steel (HSS) or cobalt wood‑drilling bit with a split‑point tip. These bits cut cleanly in wood and provide the control needed for an accurate pilot hole.

How deep should the pilot hole be for a 3/8" lag bolt?

Drill the pilot hole to a depth equal to the full length of the lag bolt, plus an extra 1/8" (3 mm) to accommodate any debris. For a typical 3‑inch lag bolt, drill about 3¼" (82 mm) deep.

Do I need a clearance hole, and if so, what size is required?

If the lag bolt passes through a metal plate or a second piece of wood, drill a clearance hole that matches the shank diameter—usually 3/8" (9.5 mm). For wood‑to‑wood connections, the pilot hole (5/16") is sufficient.

What tips can help prevent the drill bit from wandering when starting the pilot hole?

Mark the exact spot with a center punch or a nail, then start the drill at a low speed with light pressure. Using a drill press or a guide sleeve can also keep the bit straight and centered.

Meet the Reporter

Tom Woodward

Senior Reporter

Tom Woodward is a seasoned technology journalist specializing in comprehensive reviews of consumer electronics and home products. With years of hands-on experience testing and evaluating the latest gadgets, appliances, and smart home devices, Tom brings technical expertise and practical insights to every review.

Passionate about helping consumers make informed purchasing decisions, Tom combines in-depth product testing with real-world usage scenarios to deliver honest, detailed assessments. Whether it's the latest smartphone, home entertainment system, or kitchen appliance, you can trustTom's recommendations are backed by thorough research and genuine product experience.

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