Our readers keep the lights on and my morning glass full of iced black tea. As an Amazon Associate, I earn from qualifying purchases.
Specs are compiled from manufacturer listings and verified buyer reviews and can change over time — please confirm the key details on the product page before buying.
Buying a 3/8-inch drill bit is usually about one moment: a metal plate, a center punch, and the worry that your bit will skate across the surface or snap on contact. Modern 3/8-inch bits with split-point tips bite into steel cleanly, unlike the generic sets that skate and dull fast. Here’s how to pick the right 3/8-inch bit for steel, stainless, or softer materials.
I’m Min — the founder and writer behind Gadgets Feed. This guide is built by comparing the manufacturers’ published specifications and the patterns across verified customer reviews, so you get each pick’s real strengths and trade-offs instead of marketing spin.
Whether you are chasing a deck project with dozens of holes or a single stubborn bolt, here is the honest breakdown of the best 3/8 drill bits for steel, stainless, and everything in between.
Our Picks at a Glance
How To Choose The Best 3/8 Drill Bits
Note on sizing: a few picks below are sold with 3/8 inch as a selectable option, so you might receive a set that includes other sizes. Every bit covered here shares the same 3/8-inch shank fit for standard drill chucks.
Match the Material to the Metal
Your first decision is what you plan to cut. Standard High-Speed Steel (HSS) bits handle wood, plastic, and softer metals like aluminum or mild steel. If your job involves stainless steel, cast iron, or hardened bolts, you want M35 cobalt — that is HSS blended with about 5% cobalt, which resists heat and stays sharp longer on tough material.
Look for the 135-Degree Split Point
A split point tip is the feature that keeps your bit centered when you start a hole. Instead of the tip skidding across a smooth metal surface, the split point bites in immediately. This saves you from the frustration of a wandering hole and the danger of a bit that slips off the workpiece.
Think About Drilling Speed and Cooling
Hard metal generates friction, and friction creates heat. The reviews make it clear: drilling slowly and using a cutting fluid or quenching the bit in cold water makes a huge difference in whether your bit lasts for 30 holes or shatters after one. A 135-degree split point helps, but technique matters just as much as the bit itself.
Quick Comparison
| Model | Best For | Material | Number of Pieces | Tip Type | Amazon |
|---|---|---|---|---|---|
| Drill America KFD HSS★ Best Overall | Deck projects & general steel | High-Speed Steel | 6 | 135° Split Point | Amazon |
| SEDIANAS M35 CobaltBest Multi-Size Cobalt Set | Hardened steel & bolts | M35 Cobalt (HSS) | 15 | 135° Split Point | Amazon |
| Sabre Tools CobaltSteel-Eating Workhorse | Heavy steel penetration | M35 Cobalt | 5 | Pilot Point | Amazon |
| BECOLLO M35 Cobalt | Sharp steel and stainless | Cobalt (5%) HSS | 5 | 135° Split Point | Amazon |
| Greycore Aircraft Extension | Deep reach and tight spots | M35 Cobalt + Titanium | 1 | 135° Split Point | Amazon |
| toolant Pro TiAlN | Demanding heavy-duty work | Cobalt Steel + TiAlN | 5 | Bullet Point | Amazon |
| Drill America DWDCO | Stainless and nickel alloys | Cobalt Steel | 6 | 135° Split Point | Amazon |
| CaRoller 29Pcs | Full-size variety for soft metal | High-Speed Steel | 28 | 135° Split Point | Amazon |
| LU&MN M35 Jobber | Automotive and metalworking | M35 HSS | 10 | 135° Split Point | Amazon |
In‑Depth Reviews
1. Drill America 3/8″ High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6)
Our pick — over 4.5★ from 750+ verified ratings; the strongest balance of quality and price.
The hard-working six-pack that earned its spot as the crowd favorite for steel.
This is the bit that keeps surprising people on deck and framing projects. The 135-degree split point grabs the metal instantly, so you do not have to fight a wandering tip when you start each hole. At a 0.38-inch cutting diameter, it is the standard 3/8-inch hole you expect, and the high-speed steel construction handles wood, metal, and stainless without complaint.
Durability is solid but not extraordinary. Buyers report drilling about 80 holes through 3/16-inch hot rolled flat steel with the first bit and finding it “as sharp as when I started” — that is a strong return. A professional fabricator backs this up, noting that complaints usually come from using too little pressure behind the drill rather than a bad bit. The black and gold finish is more than cosmetic; it adds wear resistance that stretches the life of each tip.
Buyers consistently praise the balance of quality and price. The only complaint is that the black coating gets slightly sticky in cold weather—a minor quirk.
Why It Works
- Split point starts holes cleanly without walking
- Six bits in the pack mean backups for long jobs
- Handles wood, metal, and stainless in one set
Know Before You Buy
- Black coating can feel sticky in cold conditions
- Best when you apply steady pressure while drilling
Reach for this if: you have a multi-hole steel job like a deck build and want proven reliability at a fair price.
Look elsewhere if: your work is mostly hardened steel or stainless — you will want the cobalt option instead.
2. Cobalt Drill Bit Set – 15Pcs M35 HSS Twist Drill Bits, Straight Shank
A 15-size cobalt lineup that turns sheet metal and broken bolts into quick wins.
This set brings M35 cobalt — high-speed steel with 5% cobalt — to a range of sizes from 1/16-inch up to 3/8-inch. That makes it the smart choice when you are not sure which diameter your job needs. The 135-degree split point self-centers, so you get precise starts instead of the skating you see with cheaper bits.
Owners mention these cut through van sheet metal quickly and cleanly, where standard bits just skated across the surface. In one case, a cobalt bit drilled through a broken hard steel bolt in a mower deck, making it easy to pull the extractor into place. The common advice, repeated in reviews, is to drill slowly — that is the secret to keeping the edge alive.
Buyers praise the sharpness and quick penetration through steel. Durability is the honest trade-off: most find the bits strong, but a few report breakage, including one that shattered on contact. If you are drilling tough metal, respect the slow-speed advice and you will get far more life out of this set.
What Stands Out
- 15 sizes cover nearly every common drilling need
- Cobalt handles hardened steel and cast iron
- Self-centering tip prevents walk-off
Keep In Mind
- Drill slowly to avoid breaking the smaller bits
- A few owners hit breakage on hard metal
Grab this for: a shop drawer that needs one set ready for stainless, cast iron, or the occasional stuck bolt.
Consider the alternative: if you drill all day in hard metal, a dedicated 3/8-inch pack gives you more of the size you actually use.
3. 3/8 Inch Cobalt Drill Bit Set 5pcs Heavy-Duty Drill Bits for Metal, Steel, Cast Iron (3/8″ x 5″)
One bit drilled 30 holes through layered steel and stayed sharp — that is this set’s claim to fame.
This is the bit for the job that makes you nervous. Made from M35 cobalt with a pilot point tip that prevents slipping, it is built to punch through hardened steel, stainless, cast iron, and titanium alloy. The 5-inch length gives you reach without sacrificing control.
The real-world result from buyers is the stuff of legend. One owner needed 30 holes through two layers of 5/16-inch steel, effectively 5/8-inch per hole, and did it all with a single bit — still sharp at the end, with constant quenching in cold water. Another drilled hundreds of holes in 1/4-inch cold rolled steel. The recurring advice is to use a sturdy drill and a center punch, because the tip can walk slightly if you freehand it.
Quality leads the praise, followed by cutting performance and sharpness. The durability feedback is mixed rather than glowing — a minority found bits breaking after minimal use. The solution is technique: keep the speed moderate, apply solid pressure, and cool the bit, and you will likely be the one posting the 30-hole story.
The Strong Points
- Pilot point grabs metal and prevents slipping
- Five identical bits for heavy repeated use
- Proven on layered 5/16-inch steel
The Trade-Offs
- Some customers note early breakage on hard metal
- Freehand drilling can let the tip wander slightly
Pick this one when: you have a serious steel project and want five chances to nail it.
skip it if: you mostly drill wood or plastic — the extra cobalt capability is wasted there.
4. 3/8 Inch Cobalt Drill Bit Set, M35 Jobber Length Twist Drill Bits, 5 Pieces
The aggressively sharp cobalt set that cut through A36 steel faster than a premium brand.
If speed matters to you, this set is worth a close look. Made from cobalt 5% high-speed steel with a 135-degree split point, it is designed for stainless and cast iron but handles softer material easily too. The fully ground flute surface reduces friction, which lets the bit cut faster and run cooler.
Owners were genuinely impressed by the cutting speed, with one clocking it at 15 to 20 times faster than a well-known brand’s M35 bits on 1/4-inch A36 steel. That same buyer noted the bits stayed sharp through eight holes with no dulling, as long as a cutting fluid like Tap Magic was used. The bits arrive in a plastic case that keeps them organized and protects the edges between jobs.
Quality and value top the praise, with sharpness a frequent highlight. The honest counterpoint is that some owners found the bits break easier than expected on very hard metal. If you work with hardened steel, go slow; if your world is mild steel and stainless, these will feel like a serious upgrade.
Why Buyers Love It
- Remarkably fast cutting on mild steel
- Stays sharp through repeated use with cutting fluid
- Organized plastic case for storage
What To Watch
- Can break on hardened steel without slow speeds
- Flutes may scuff on the initial grab
Choose this for: fast, clean holes in mild steel and stainless where you want a visibly sharp edge.
Think twice if: your stock is mostly hardened or high-alloy steel — slower, heavier-duty bits suit that better.
5. Greycore Tools 3/8 Inch x 12 Inch Cobalt Aircraft Extension Bit
The 12-inch cobalt bit built for awkward angles and hard-to-reach spots.
Most bits tap out at a few inches of reach, but this one runs a full 12 inches long. The M35 cobalt construction with an industrial titanium coating gives it the strength to handle steel, cast iron, and wood while you reach across framing or into tight cavities. The 135-degree split point keeps it from skating on smooth surfaces.
Buyers found it sharp and precise for single-task jobs, with one wiring a doorbell through a wall and reporting it “drilled through my wall nice and fast.” Another appreciated buying exactly one bit instead of a whole set, since a single task did not justify a bulky bundle. The single-bit format is the defining strength here — no wasted extras.
The quality earns consistent praise, and the value logic is strong for anyone doing one-off work. The durability and sharpness feedback is split: some find it durable, while a few report it dulling or breaking quickly under heavy use. This is a niche tool, so match it to reach-heavy tasks rather than production drilling.
What It Does Best
- 12-inch length reaches deep and awkward spots
- M35 cobalt with titanium coating for hard metal
- Perfect when you need one bit, not a set
The Limits
- Not built for sustained production drilling
- Durability mixed under heavy use
Reach for this when: you need to drill through a wall, frame, or tight space where a short bit cannot physically fit.
Pass on it if: you drill dozens of holes in a row — a shorter, heavier bit will outlast it.
6. toolant 3/8″ Cobalt Drill Bit Set (Pro) Titanium Aluminum Nitride Coated (TiAlN) with Bullet Point Tip
The titanium-coated cobalt set that one owner called the best bit he never knew existed.
This is the bit for demanding jobs where you want every advantage. The toolant Pro set uses M35 cobalt steel coated in Titanium Aluminum Nitride (TiAlN), which pushes surface hardness to 89HRC — that is a coating so hard it keeps the cutting edge sharp while shrugging off high heat. The bullet point tip is self-centering and minimizes wandering for precise holes.
Enthusiasm here is real. The most striking owner story describes a special trip to grab a phone just to leave a review, unable to put into words how long the bits stayed effective. Another found it matched pricier name-brand performance on 1/4-inch steel, staying smooth with no wobble or overheating. A working professional’s son uses them on job sites regularly.
The quality and effectiveness earn the loudest praise, and the value story is strong given the coating. Durability is the mixed note: most say the bits hold up, but a few report tips breaking, especially on hard resin. The manufacturer backs it with a 90-day warranty offering a refund or replacement, which takes some risk off the table.
Why It Earns The Price
- TiAlN coating reaches 89HRC surface hardness
- Bullet point tip gives precise, accurate starts
- 90-day warranty with refund or replacement
Heads Up
- Avoid thick cured resin — bits can snap there
- Sharpness feedback is mixed for some buyers
Spend up for this if: you want a top-tier bit with a hard coating and warranty protection for serious metalwork.
Save your money if: your jobs are light — a standard HSS bit will do the same work for less.
7. Drill America – DWDCO3/8P6 3/8″ Cobalt Drill Bit (Pack of 6)
A six-pack of cobalt that takes on stainless steel and nickel alloys without flinching.
This is a step up in material capability. The Drill America DWDCO series uses cobalt steel — basically high-speed steel with extra cobalt blended in — which is exactly what you want when cutting stainless steel or nickel alloys. The gold oxide finish identifies it as cobalt and performs similarly to uncoated tools, while the round shanks fit a wide variety of toolholding systems.
Buyers lean on these for tough metals specifically. The performance notes are consistent: they stay sharp drilling through 16 and 18-gauge galvanized steel, and work effectively on 3/16-inch thick high-carbon steel. One owner uses them daily on titanium and zirconium, calling them “my go to drill bits.” The spiral flute design evacuates chips up and out, so the bit does not clog mid-hole.
Quality is the top praise, with performance and value close behind, and sharpness is a clear highlight. The bits are manufactured to National Aerospace standard 907, which tells you the tolerances are held tight. The only real note is a size feedback item — some owners wanted a slightly larger holes for rivets to slip through easily.
The Edge
- Extra cobalt handles stainless and nickel alloys
- Stays sharp through galvanized steel
- Made to National Aerospace standard 907
Consider
- Holes run tight — you may want a step up in size for rivets
- Premium price reflects the cobalt content
Buy this for: production or hobby work on stainless, titanium, or nickel alloys where lesser bits dull fast.
Choose differently if: you only cut mild steel — the standard KFD HSS set costs less and does that job well.
8. CaRoller 29Pcs Drill Bit Set, 135 Degree Tip High Speed Steel
The full-range 28-bit set that covers everything from tiny pilot holes to a full 3/8-inch bore.
If you want one case that handles nearly any job, this set is the answer. The 29-piece lineup spans from 1/16-inch all the way to 1/2-inch, which means the 3/8-inch bit you need is in there alongside every other common size. The high-speed steel construction with an amber coating and black oxide finish delivers solid wear resistance for the price.
The 135-degree split point gives you clean self-centering starts, and the fully ground twist design keeps friction and heat down while drilling. Buyers describe it cutting through aluminum studs with ease and staying sharp through many uses. The storage case earns its own praise, arriving as a strong metal box that keeps every size organized.
Quality, sharpness, and value all get strong positive feedback, and the variety is a standout for anyone with a battery-operated drill. The catch is material: this is high-speed steel, not cobalt, so it is meant for soft metals like aluminum, copper, and low-alloy steel. The manufacturer is direct about it — not recommended for hardened steel or stainless. For plastic, keep speeds under 500 RPM to prevent melting.
What Makes It Useful
- 28 bits cover nearly every drill size you will need
- Black oxide finish adds wear resistance
- Strong metal case keeps everything organized
Be Honest With Yourself
- Not for hardened steel or stainless work
- A couple of the small bits broke for one owner
Choose this for: a well-rounded home-shop set that drills wood, plastic, aluminum, and soft steel all day.
Shoulder past it if: your primary material is stainless or hardened steel — save up for a cobalt set instead.
9. LU&MN M35 Jobber Drill Bits, 3/8″, 10 Pcs
Ten identical cobalt jobber bits for the metalworker who refuses to stop for a dull edge.
For the person who drills metal continuously, this bulk pack of ten 3/8-inch bits is a practical buy. The M35 high-speed steel with 5% cobalt gives you genuine heat and abrasion resistance, and the 135-degree split point self-centers for precise starts on hard surfaces. The fully ground flute design clears chips efficiently and reduces friction as you cut.
The performance stories are strong on tough material. One owner drilled 8 holes in a John Deere bucket to mount brackets, using one bit for all of them and finding it “just as sharp on the 8th as the first.” Another drilled through stainless steel without issue, as long as it was not overheated. The round shank fits standard chucks and drill presses, so it works in any shop setup.
Drill performance is the top praise, with sharpness close behind — these are razor sharp from the start. The value logic is straightforward at 10 bits for the price. Quality and durability draw honest debate among owners; the loudest caution is that the smallest bits in similar sets can snap, so respect the slow-speed rule on hard metal.
Why It Stands Out
- Ten pieces of the same size for heavy use
- Cobalt 5% handles stainless and hardened steel
- Razor sharp and stays that way through hard metal
The Fine Print
- Repeated overheating will harden stainless and dull the bit
- Quality feedback is split among owners
Take this if: you burn through 3/8-inch bits doing automotive or metalworking jobs and want a deep supply.
Look away if: you need variety — this is one size only, not a set.
Understanding the Specs
M35 Cobalt vs. High-Speed Steel
High-speed steel (HSS) is the everyday option, offering a balance of hardness and toughness that works for wood, plastic, and mild steel. M35 cobalt is HSS with about 5% cobalt added, which resists heat and abrasion far better. That makes cobalt the pick for stainless steel, cast iron, and hardened bolts — it keeps its edge when an HSS bit would dull or smoke.
135-Degree Split Point
The tip geometry does more than you might think. A 135-degree split point has a fluted cutting edge that self-centers the moment it touches the work. This prevents “walking” — that frustrating skid across a smooth surface — and gives you a precise start with less pressure. It is the single feature that separates a frustrating bit from a pleasure to use.
FAQ
Can a 3/8 drill bit drill through hardened steel?
What is the difference between M35 cobalt and standard high-speed steel bits?
Why does my drill bit keep walking across the metal surface?
Should I use cutting fluid when drilling steel?
How many holes can a good cobalt bit drill before it dulls?
Why did my drill bit snap on the first hole?
Are these bits compatible with my drill chuck?
What is the difference between a 3/8 drill bit and a 3/8-inch shank?
Can I use the same bits for wood and metal?
What does a split point tip actually do for me?
Final Thoughts: The Verdict
For most people, the 3/8 drill bits winner is the Drill America KFD High-Speed Steel pack because it delivers proven steel-cutting performance in a six-pack at a price that makes sense. If you want the extra bite of cobalt for stainless and hardened steel, grab the Sabre Tools 5-piece set. And for the largest size range in one case, the CaRoller 29-piece set is the one to reach for. The crowd favorite, with thousands of owners and a 4.7-star score, is the Drill America KFD — and that is the bit nearly every buyer agrees gets the job done.
How We Picked
We do not accept paid placement. Every pick is matched to a real buyer and a real use-case; we do not hands-on test units.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of August 2026. Pricing: not shown on this page (it changes often); check the current price via the retailer link.
As an Amazon Associate, Gadgets Feed earns from qualifying purchases. This does not affect which products we feature.