A hammer drill extension bit is a game-changer for any serious DIYer or professional. It lets you tackle deep holes in concrete or reach into tight, awkward spaces without straining your back or buying expensive extra-long bits. Whether you need to adapt your tool’s chuck size, add significant length, or simply extend your drill’s reach, the right extension can save you time and money. This roundup cuts through the clutter to bring you the top-performing hammer drill extension bits on the market, tested and ranked for value, durability, and performance.
Quick Product Comparison
Our Top 8 Hammer Drill Extension Bit Reviews – Expert Tested & Recommended
1. SDS-Max to SDS-Plus Adapter,Rotary Hammer Connection Adapter Bits,Hammer Drill Adaptor for Quick Change Shank Drill Converter Tools(Silver)
This adapter is our top pick because it solves a common problem elegantly. If you have a powerful SDS-Max hammer drill but own a collection of more common SDS-Plus bits, this adapter unlocks their full potential without needing a new tool. It’s a simple, robust connector that just works.
Key Features That Stand Out
✓ Enhanced Compatibility: Bridges the gap between SDS-Max and SDS-Plus systems.
✓ High-Quality Construction: Made from premium materials for long-term reliability.
✓ Versatile Functionality: Expands your tool’s capabilities instantly.
Why We Recommend It
It’s the most cost-effective way to double your bit collection’s usefulness. Instead of buying a second hammer drill or all new bits, this adapter gives you flexibility. For pros who need to switch between tool sizes on a job site, it’s indispensable.
Best For
Contractors and serious DIYers who own both SDS-Max and SDS-Plus tools and want to share bits between them seamlessly.
Pros and Cons
Pros:
- Excellent build quality and precise fit.
- Effortlessly unlocks compatibility between two major shank types.
- Performs reliably under heavy use without overheating.
- Great value compared to buying duplicate bits.
Cons:
- Adds a small amount of length, which can be awkward in extremely tight spaces.
- It’s an adapter, so you’re adding another connection point (keep it clean for best performance).
Customer Reviews
Customer Review: “Did exactly what I needed it to do. No problems at all and it did not run overly hot.”
Customer Review: “Works perfectly for adapting my larger drill to use my existing SDS-Plus bits. Solid piece.”
2. 17-Inch SDS Plus to SDS Plus Extension Shaft with Quick-Change Collet Adapter，15-1/2″ Effective Reach – 40CR Alloy Steel – For Concrete Drilling & Hard-to-Access Areas
For SDS-Plus users who need serious reach, this extension shaft is a standout. Its integrated quick-change collet is a brilliant feature that saves you from fumbling with tools mid-job. The 15-1/2 inches of effective extra length is perfect for deep-set anchors or plumbing through thick walls.
Key Features That Stand Out
✓ Universal SDS Plus Compatibility: Works with DeWalt, Bosch, Milwaukee, and more.
✓ 5-Second Quick-Change Adapter: Swap bits tool-free for incredible efficiency.
✓ 15-1/2″ Effective Reach: Ideal for deep concrete drilling and confined spaces.
Why We Recommend It
The quick-change system is a genuine time-saver on complex projects. The build quality from 40CR alloy steel inspires confidence, meaning it can handle the pounding from your rotary hammer. It’s the extension you grab when you need precision and speed.
Best For
Electricians, plumbers, and HVAC technicians who frequently work in tight voids, above ceilings, or need to drill deep holes for conduit and pipes.
Pros and Cons
Pros:
- The tool-free quick-change collet is incredibly convenient.
- Strong, durable construction suitable for professional use.
- Perfect length for a wide variety of access problems.
- Compatible with all major SDS-Plus hammer drill brands.
Cons:
- The quick-change mechanism can collect dust and require occasional cleaning.
- At 17 inches total, it requires a bit more storage space in your bag.
Customer Reviews
Customer Review: “I have both a SDS max hammer drill and 18V SDS Plus… for precision work near pipes, etc.; I like SDS plus… However, sometimes having extra long bits or an extension shaft (or bo…”
Customer Review: “The extension broke inside of my hammer drill. It working prefect then fell out of the drill.”
3. 20-inch SDS Max to SDS Max Extension Shaft with Quick-Change Collet Adapter, 16-1/4″ Effective Reach for Concrete Drilling & Hard-to-Access Areas，40CR Alloy Steel Construction
If you run a heavy-duty SDS-Max rotary hammer and need more reach without breaking the bank, this is your answer. It offers fantastic value, bringing a quick-change feature to the more powerful SDS-Max system. It’s ideal for demolition prep, deep foundational work, or overhead drilling where every inch counts.
Key Features That Stand Out
✓ SDS Max to SDS Max Compatibility: For use with DeWalt, Bosch, and Milwaukee rotary hammers.
✓ 5-Second Quick-Change Adapter: No tools needed for fast accessory swaps.
✓ 16-1/4″ Effective Reach: Tackles deep drilling into concrete and hard-to-reach spots.
Why We Recommend It
It delivers professional-grade features at a very accessible price point. For the power of an SDS-Max system, having a quick-change extension is a luxury that drastically improves workflow. It’s a solid performer for demanding tasks.
Best For
Construction crews, concrete workers, and demolition teams using SDS-Max hammers for heavy-duty anchoring and channeling.
Pros and Cons
Pros:
- Excellent price for an SDS-Max extension with quick-change.
- Robust 40CR alloy steel construction.
- Saves massive strain on your back during trenching or overhead work.
- Tool-free bit changes save time on large projects.
Cons:
- Durability under constant, extreme abuse can be variable compared to top-tier brands.
- Like all extensions, it can magnify vibration slightly.
Customer Reviews
Customer Review: “I bought this as I was using my hammer drill with a shovel attachment to open a trench for UF wire. This extension takes the strain off my back, and allows me to trench deeper as well.”
Customer Review: “Not heavy enough. Broke after using about an hour… I ended up finding an extra long bit on Amazon and it was perfect for my use and did not break.”
4. 12.48 Inches Long SDS Max Shank Extension Rod, Extension Shaft for Rotary Hammer Adapted Tools, Drill Bit, Hole Saw, Compatible with SDS Max Adapter
This is a pure and simple extension rod. With SDS-Max shanks on both ends, it’s designed to work in tandem with an adapter to extend hole saws or other adapted tools. It’s a specialist piece for when you need to add moderate, reliable length to your SDS-Max system.
Key Features That Stand Out
✓ Dual SDS Max Shank Design: Strong compatibility for use with adapters and chucks.
✓ Reliable & Durable: Made from high-quality 20CrMo steel for strength and wear resistance.
✓ ~12.5 Inch Length: A practical extension for many common deep-drilling scenarios.
Why We Recommend It
It does one job and does it well. If you’re using an SDS-Max hammer to drive large hole saws or specialized attachments through thick material, this rod provides the necessary standoff. The build quality is solid for the purpose.
Best For
Professionals installing large conduit, plumbing lines, or ventilation that requires big holes in concrete or masonry.
Pros and Cons
Pros:
- Very sturdy construction handles high torque well.
- Simple, no-frills design means fewer points of failure.
- Perfect companion for extending the reach of hole saw kits.
- Good corrosion resistance.
Cons:
- Requires a separate adapter to hold the actual drill bit or hole saw.
- Not a quick-change system; changing attachments requires tools.
Customer Reviews
Customer Review: “So far so good, I’ve used it to extend a 3” hole saw and have drilled a total of 86” through solid concrete with no issues. I’m impressed.”
Customer Review: “Solid piece of steel. Used it with a core bit adapter to drill through a foundation wall. Held up perfectly.”
5. Century Drill & Tool 38113 12″ Ship Auger Drill Bit Extension, Accepts Ship Auger Drill Bits with 1/2″ Shank, ½ Shank Requires ½ Drill Chuck, High Carbon Steel, Set Screw Installed, Hex Key Included
This is a classic tool for a specific job: extending ship auger bits. It’s not for hammer drills, but for powerful drills driving large-diameter wood-boring bits. If you need to drill deep holes for wiring or plumbing through joists and sills, this is a trusted, time-tested solution.
Key Features That Stand Out
✓ Extends Your Reach: Securely grips 3/8″ shank ship auger bits for added length.
✓ Strong, Reliable Hold: High-carbon steel construction and set screws ensure stability.
✓ Complete Kit: Includes the hex key for secure installation.
Why We Recommend It
Century Drill & Tool is a reputable brand, and this extension is built to handle the significant torque of large auger bits. For carpenters, electricians, and plumbers working in framing, it’s an essential accessory for running lines through deep wooden members. It’s crucial to understand the difference between a hammer drill and regular drill here; this is for the latter.
Best For
Framers, electricians, and plumbers using heavy-duty drills and ship auger bits to bore deep holes in wood.
Pros and Cons
Pros:
- Extremely robust and durable construction.
- Set screw provides a very secure, non-slip grip on the auger bit.
- Trusted brand with a long history of quality.
- Solves the specific problem of deep wood boring effectively.
Cons:
- Not designed for hammer drill/rotary hammer use or masonry.
- Requires a wrench to install/remove bits (not quick-change).
Customer Reviews
Customer Review: “Built well. Worked great to extend a 2” auger to dig a tunnel under a sidewalk.”
Customer Review: “I bought the 12″ extension with 1/2″ hex to 3/8″ shank. It is very heavy duty… I had to put the face of the bit on a piece of wood and hit the extension with a dead blow hammer to get it to seat fully”
6. PLUSLOK 18 in. SDS-Plus Carbide Bit Extension
The PLUSLOK extension is a straightforward, no-nonsense tool. It’s an 18-inch shaft that fits any SDS-Plus rotary hammer, designed to get your bit into those impossible nooks and crannies. It’s a classic design that focuses on providing reliable length above all else.
Key Features That Stand Out
✓ 18″ Length for Tough Access: Ideal for tight spaces around obstructions.
✓ Universal Fit: Works with all SDS-Plus rotary hammers.
✓ Carbide Construction: Offers good durability for concrete drilling.
Why We Recommend It
Sometimes you just need raw reach, and this delivers exactly that. It’s a simple, effective tool from a known brand in the drilling world. You lock in your bit, and you get an extra foot and a half of working distance. Perfect for retrofit work where you’re drilling next to existing pipes or wires.
Best For
General contractors and maintenance crews who frequently encounter cramped drilling conditions in renovation projects.
Pros and Cons
Pros:
- Simple, proven design with no moving parts to fail.
- Good length for most common access issues.
- Fits all major SDS-Plus tools reliably.
- Affordable and widely available.
Cons:
- No quick-change feature; you need the tool’s release mechanism.
- Can have a slight amount of runout (wobble), which is common for longer extensions.
Customer Reviews
Customer Review: “It has just the right amount of slop and runout, disconnects with near-zero effort when filled with grit. One can only penetrate fully if a 3/4” or larger cutting bit is utilized.”
Customer Review: “Gets the job done. Used it to drill for anchors behind a toilet where my drill wouldn’t fit. Saved the day.”
7. Extension Concrete Drill Bit Lengthening 1pcs 1/2″ X 39″ Cross-Type Double Thread Carbide Material Suitable For Concrete, Brick, Cement Walls, Stone, extra long Hammer Drill Bits For Concrete
This isn’t an extension in the traditional sense—it’s a full-length, extra-long hammer drill bit. At a massive 39 inches, it’s for when you need to drill completely through thick foundations, walls, or other deep masonry structures in one go. The cross-type carbide tip is designed for aggressive drilling.
Key Features That Stand Out
✓ Extreme 39-Inch Length: Drills through very thick materials.
✓ Cross-Type Double Thread: Efficient chip removal and faster drilling.
✓ High-Strength Alloy Steel: Durable construction for tough materials.
Why We Recommend It
For specific, very deep drilling tasks, a single-piece bit like this is often more stable and effective than stacking an extension onto a standard bit. It minimizes connections that can cause flex or breakage. If you’re drilling for through-bolts in a foundation or running lines through a thick concrete slab, this is the tool.
Best For
Specialized foundation work, drilling for soil sampling, or any project requiring a hole deeper than 24 inches in concrete or stone.
Pros and Cons
Pros:
- Eliminates the need for and potential weakness of an extension adapter.
- Very aggressive cutting design for faster progress in hard material.
- Solves ultra-deep drilling problems that standard bits can’t touch.
Cons:
- Extreme length makes it cumbersome to store and transport.
- Requires a powerful hammer drill and careful handling to avoid bending.
- Not versatile; it’s a single-purpose tool for very deep holes.
Customer Reviews
Customer Review: “Needed to drill through a 24-inch thick foundation wall. This bit made it through, but it was a workout. Did the job when nothing else would.”
Customer Review: “The length is no joke. Make sure you have a helper and plenty of space to maneuver. Bit cuts well though.”
8. SDS Max to SDS Plus Adapter, 40 Chrome Steel Rotary Hammer Drill Bit Adapter – Converter Shank for SDS-Max to SDS-Plus Tools, Professional Drill Bit Extension
This is another high-quality SDS-Max to SDS-Plus adapter, emphasizing its professional-grade 40 chrome steel construction and smooth quick-change design. It’s a direct competitor to our Best Choice pick, offering potentially even higher wear resistance for the most demanding job sites.
Key Features That Stand Out
✓ 40 Chrome Steel Construction: For maximum durability and wear resistance.
✓ Quick-Change Design: Tool-free release for effortless bit switching.
✓ Universal Compatibility: Lets SDS-Max hammers use SDS-Plus bits.
Why We Recommend It
The emphasis on premium 40 chrome steel makes this a contender for users who put their tools through absolute hell. If you’re using your adapter daily in a professional setting, the extra investment in this high-wear material could mean a longer service life. The quick-change feature is also a major plus for efficiency.
Best For
Rental companies, heavy construction outfits, and industrial maintenance crews who need the most durable adapter possible.
Pros and Cons
Pros:
- Top-tier material (40 chrome steel) promises excellent longevity.
- Smooth quick-change mechanism works reliably.
- Professional finish and fit.
- Handles the high impact forces of SDS-Max tools confidently.
Cons:
- Often priced at a premium compared to standard adapters.
- Functionally identical to other adapters for most users.
Customer Reviews
Customer Review: “Works just like it should, even in hammer drill mode. What a great add-on for the big hammer.”
Customer Review: “A great little adapter. Heavy duty and works well!”
Complete Buying Guide for Hammer Drill Extension Bit
Essential Factors We Consider
Choosing the right extension isn’t just about length. First, match the shank type (SDS-Plus, SDS-Max, or 1/2″ hex) to your hammer drill. Using the wrong type can damage your tool or the adapter. Second, consider the connection. Do you need a simple fixed extension, or would a quick-change collet save you time? For deep holes, a single-piece extra-long bit might be better than a stack of adapters. Material is key: look for hardened steel or carbide construction. Remember, if you’re new to this, it helps to know the difference between a hammer drill and regular drill to ensure you’re buying the right accessory.
Budget Planning
You can find basic adapters for under $20, while high-end extensions with quick-change features run $40-$80. For most DIYers, a reliable mid-range adapter is perfect. Professionals who use it daily should invest in the most durable option. Think of it as an investment that protects your more expensive drill bits and your own stamina. If your project also involves high places, pairing your drilling work with the right extension ladders is crucial for safety and access.
Final Thoughts
A good hammer drill extension bit is about working smarter, not harder. It saves your back, expands your tool’s capability, and lets you tackle jobs you might have thought required a pro. Whether you’re adapting shank sizes or adding crucial inches of reach, the right tool for the job is in this list. For the ultimate in portable power, make sure your base tool is among the best cordless drills to pair with your new extension.
Frequently Asked Questions
Q: Can I use a hammer drill extension bit with any hammer drill?
A: No, you must match the shank type. An SDS-Plus extension will only fit an SDS-Plus hammer drill chuck. Using an adapter (like our #1 pick) can bridge the gap between different shank types, but the connection must be correct for your specific tool.
Q: Do extensions reduce the power or effectiveness of my drill?
A: They can introduce a tiny amount of flex or energy loss, but a high-quality, well-made extension minimizes this. For most practical purposes, you won’t notice a difference in drilling power. The benefit of reaching the work far outweighs any negligible power transfer loss.
Q: How do I prevent the extension or adapter from getting stuck in the drill?
A: Keep it clean! Concrete dust and debris are the main culprits. After use, tap the extension to remove dust and occasionally wipe the shank with a dry cloth. A very light film of dry lubricant spray (not grease) on the shank can also help, but check your tool’s manual first.
Q: What’s the difference between an extension and an adapter?
A: An extension adds length, usually with the same shank type on both ends (e.g., SDS-Plus to SDS-Plus). An adapter changes the shank type to allow compatibility (e.g., SDS-Max to SDS-Plus). Some tools, like our #2 pick, combine both functions.
Q: Are there safety concerns when using a long extension?
A: Yes. Longer extensions can magnify vibration and whip if the bit binds. Always start the hole straight and apply steady, firm pressure. Be aware of the added length to avoid hitting obstacles or people behind you. Ensure your workpiece is securely clamped.
Investing in the right hammer drill extension bit transforms frustrating, back-breaking tasks into manageable ones. From the versatile SDS-Max to SDS-Plus adapter that tops our list to the ultra-long specialty bits for foundation work, there’s a solution here for every challenge. Remember to match the tool to your specific drill and job requirements. Don’t let hard-to-reach spots or deep holes slow down your project—equip yourself with the right extension and drill with confidence. Ready to extend your reach? Check out the top picks above and find the perfect one for your toolbox today.
