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.
Drilling through stainless steel can burn up bits, snap them off, or make the tip slide across the surface instead of biting in. Most general-purpose bits lack the hardness to cut through stainless steel’s work-hardened surface without overheating. This guide reviews cobalt and high-speed steel bits that handle stainless, focusing on material composition and cutting geometry to avoid bits that dull after one hole.
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 drilling a few holes in thin gauge stainless or need to punch through a thick steel plate, the right bit for drilling stainless steel depends on a few critical specs: the cobalt percentage, the point angle, and the shank design — and we break down exactly what each of those means for your work.
Quick Picks
- (20PCS) 3/16″ Cobalt Drill Bit, HSS M35 Metal Drill Bits for Steel, Stainless Steel, Cast Iron, Hard Plastic and Wood — Best Overall
- Narwhal 1/2 Inch Cobalt Drill Bits (3 Pack – Industrial Grade M35 Cobalt) 6″ Length & 135 Degree Split Point — Industrial Pick
- (20PCS) 1/8″ Cobalt Drill Bit, HSS M35 Metal Drill Bits for Steel, Stainless Steel, Cast Iron, Hard Plastic and Wood — Precision Starter
- Luckyway 3/16 Inch Cobalt Drill Bits (10 Pack), M35 HSS Metal 3/16″ Drill Bit Titanium Coated for Hard Metal — Grip-Tight Design
- 11/32 Inch Cobalt Drill Bit Set, M35 Jobber Length Twist Drill Bits, Suitable for Drilling in Hard Metal (5 Pieces) — Steel Plate Specialist
- CaRoller 29Pcs Drill Bit Set, 135 Degree Tip High Speed Steel with Black and Gold Finish (1/16″-1/2″) — Full Kit
How To Choose The Best Bit For Drilling Stainless Steel
Choosing the wrong bit for stainless steel often results in a snapped bit and ruined workpiece. Understanding bit markings is key to selecting the right one.
Look for the Cobalt Percentage
Stainless steel work-hardens as you drill, so the bit must remain hard enough to cut continuously. Bits stamped M35 High Speed Steel contain 5% cobalt, which lets them hold their edge at the high temperatures that stainless generates. Bits made from plain HSS (high-speed steel) without cobalt lose their temper quickly and dull in just a few holes — you want at least 5% cobalt for stainless.
Check the Point Geometry
A standard 118-degree point tends to walk on hard metal, making precise hole starts difficult. A 135-degree split point is the industry standard for stainless steel, as its self-centering design bites immediately and prevents wandering, eliminating the need for a center punch.
Match the Shank to Your Chuck
Most stainless steel bits have a straight round shank that fits standard 3-jaw chucks. Some premium bits use a 3-flat shank design — with three flat surfaces ground into the shank — that locks tighter into the chuck and reduces the chance of the bit spinning in place when you apply pressure.
Quick Comparison
On smaller screens, swipe sideways to see the full table.
| Model | Best For | Number of Bits | Cutting Diameter | Material Type | Amazon |
|---|---|---|---|---|---|
| (20PCS) 3/16″ Cobalt Drill Bit, HSS M35 | High-volume drilling of 3/16″ holes | 20 | 4.76 mm | Cobalt (M35) | $20.99Amazon |
| Narwhal 1/2 Inch Cobalt Drill Bits (3 Pack) | Large diameter holes in thick steel | 3 | 0.5 Inches | Cobalt, High Carbon Steel | $19.99Amazon |
| (20PCS) 1/8″ Cobalt Drill Bit, HSS M35 | Small precise pilot holes in steel plate | 20 | 0.13 Inches | Cobalt (M35) | $14.99Amazon |
| Luckyway 3/16 Inch Cobalt Drill Bits (10 Pack) | Anti-slip drilling with titanium coating | 10 | 0.19 Inches | Cobalt (M35) with Titanium Nitride coating | $14.99Amazon |
| 11/32 Inch Cobalt Drill Bit Set, M35 (5 Pieces) | Medium duty metal plate drilling | 5 | 8.57 mm | Cobalt Steel (M35) | $17.99Amazon |
| CaRoller 29Pcs Drill Bit Set, Black and Gold | Professionals needing a 1/16″-1/2″ range | 29 | 0.06 Inches | High Speed Steel (HSS) | $39.99Amazon |
In‑Depth Reviews
5. (20PCS) 3/16″ Cobalt Drill Bit, HSS M35 Metal Drill Bits for Steel, Stainless Steel, Cast Iron, Hard Plastic and Wood
Twenty pieces of M35 cobalt at 3/16-inch that one buyer used to drill 10 holes through a steel plate with a single bit.
This set hits the balance for anyone drilling a lot of 3/16-inch holes in stainless steel, because you get 20 identical bits so you do not stop to resharpen mid-project. The bits are made from industry-grade M35 High Speed Steel containing 5% cobalt, which lets them hold an edge much longer than plain HSS bits when cutting hard metal. The 135-degree split point on each bit means you can start a hole right where you want it without the tip skating across the surface.
Reviewers specifically mention that these drilled through a 1/8-inch steel plate with no problem, with one buyer noting a single bit handled all 10 holes and stayed as sharp at the end as at the start. The bits come in a plastic storage case for easy organization. Compared to the 20-piece 1/8-inch RCINDUS set, this 3/16-inch version gives you a 4.76 mm cutting diameter versus 0.13 inches on the smaller set, so it suits standard fastener-sized holes better than the thinner pilot-hole diameter of the smaller set.
Plenty of backups: With 20 bits in one box, you do not need to baby each one — just swap in a fresh bit when it starts to feel dull, and keep drilling.
Reach for this if: you need a bulk supply of solid 3/16-inch cobalt bits for repeated stainless steel drilling and do not want to pay per-bit pricing.
Look elsewhere if: you need a single large-diameter hole bigger than 3/16-inch — this set tops out at 3/16-inch.
4. Narwhal 1/2 Inch Cobalt Drill Bits (3 Pack – Industrial Grade M35 Cobalt) 6″ Length & 135 Degree Split Point
A pack of three half-inch cobalt bits that one reviewer noted stayed sharp after drilling 80 holes in thin stainless steel.
When you need to drill a large hole through stainless, a thin 1/8-inch bit will not work, and this pack gives you three 1/2-inch diameter M35 cobalt bits that are 6 inches long with a 4-inch flute length. The 135-degree split point helps the bit self-center so you do not need a center punch for every hole, and the fully ground construction means the cutting diameter is precise. Compared to the 20-piece 3/16-inch RCINDUS set above, the Narwhal bits are 1/2 inch in diameter and come as a 3-pack, versus 3/16 inch and 20 pieces for the RCINDUS set, which makes sense only if you specifically need large bores for conduit or hardware mounting.
Buyers report that these bits drilled through 3/8-inch thick steel at a 25-degree angle without issue, and one buyer mentioned they drilled 70+ holes in thin stainless steel and still found the bits sharp after 80 holes. The bits come in a tough plastic storage case to keep them organized, and the brand backs the purchase with a USA-based customer service team.
For the big jobs: At 0.5 inches cutting diameter, these are the widest bits in this entire lineup — the right choice for pass-through holes for conduit, cable, or hardware mounting.
Grab these for: drilling large 1/2-inch holes through stainless steel plate or thick steel, where you need the extra length to reach through material.
Skip if: your project calls for small pilot holes under 1/2-inch — you will waste money on diameter you cannot use.
1. (20PCS) 1/8″ Cobalt Drill Bit, HSS M35 Metal Drill Bits for Steel, Stainless Steel, Cast Iron, Hard Plastic and Wood
Twenty 1/8-inch cobalt bits that outperformed a name-brand Milwaukee bit and came in at a lower cost per piece.
Small-diameter bits are the ones that snap most often when drilling hard metals, so having 20 spares in a box is a practical advantage. These bits use the same M35 High Speed Steel with 5% cobalt as the larger RCINDUS set, and they also have the 135-degree split point for self-centering. The cutting diameter is 0.13 inches, versus 0.5 inches for the Narwhal 1/2-inch bits, so these are strictly for pilot holes and small fasteners.
A reviewer who needed to drill through a 1/8-inch steel plate reported that one bit drilled all 10 holes and performed just as well on the last hole as on the first. Another buyer mentioned these cheap bits outperformed a Milwaukee bit, with each bit drilling roughly 25 stripped screw heads before dulling. The bits are factory-ground with diameter accuracy controlled to within -0.03mm, so you get consistent sizing across the entire pack.
Why you want a big pack
- 20 bits mean you can drill all day without stopping to sharpen
- 135-degree split point prevents walking on hard surfaces
- Diameter held within -0.03mm for consistent fit
The size limitation
- Only 1/8-inch diameter — too small for most fastener-ready holes
- No larger sizes included in this set
Best for: drilling pilot holes in stainless and steel plate before stepping up to a larger diameter, or for removing broken screws.
Not for: anyone who needs finished holes larger than 1/8-inch without buying a second set.
2. Luckyway 3/16 Inch Cobalt Drill Bits (10 Pack), M35 HSS Metal 3/16″ Drill Bit Titanium Coated for Hard Metal
A 10-pack with a titanium nitride coating and a 3-flat shank that locks into the chuck to stop spin-out.
What makes this set different from the other 3/16-inch packs is the shank design. Instead of a standard round shank that can slip inside the chuck under heavy load, these bits have three flat surfaces ground into the shank that the chuck jaws grip tighter — so the bit stops spinning in place when you push hard into stainless. The bits also carry a titanium nitride coating over the M35 cobalt base, which adds surface hardness and reduces friction so the bit runs cooler during drilling.
The 10 pieces give you a good balance of quantity without the bulk of a 20-pack, and they come in a durable plastic case. The bits are 3/16-inch (0.19 inches) in diameter, which fits common screw and bolt pilot needs.
Built to grip
- 3-flat shank design stops bit slippage in the chuck
- Titanium coating helps the bit run cooler and stay sharp longer
- 10-bit count covers most projects without overbuying
One size only
- Single 3/16-inch diameter — no smaller or larger bits in the set
- Coating may wear off after repeated use on abrasive stainless
Pick this if: you have had drill bits spin loose in your chuck before and want the extra locking security of a 3-flat shank.
Pass if: you need a variety of diameters — this set only gives you one size.
3. 11/32 Inch Cobalt Drill Bit Set, M35 Jobber Length Twist Drill Bits, Suitable for Drilling in Hard Metal (5 Pieces)
Five cobalt bits at 11/32-inch that one buyer used to drill 11 holes through thick steel plate while competitor bits failed after one.
This set fills the gap between the small 1/8-inch precision bits and the heavy 1/2-inch industrial bits. At 8.57 millimeters in diameter, these bits sit between the RCINDUS 3/16-inch bits at 4.76 mm and the Narwhal 1/2-inch bits at 0.5 inches, giving you a mid-range size suitable for bolt and fastener holes without needing an industrial chuck. The bits are M35 cobalt steel with a 135-degree split point and are manufactured to ANSI B94-11M standards.
A reviewer who drilled through thick steel plate reported getting 11 holes from 3 bits, while a competitor’s pilot-tip bits failed after just 1 hole. However, another buyer noted that these bits struggled with fully hardened steel like leaf springs on an F150 and stressed that low RPM and constant oiling are essential. The set comes with just 5 bits in a plastic case, so you get fewer spares than the 10- or 20-packs.
Mid-range workhorse: At 11/32-inch, this diameter is versatile enough for many construction and repair tasks while being tough enough to survive thick steel if you use oil and slow speed.
Best for: drilling medium-diameter holes in mild steel and stainless plate where you need a precise 11/32-inch finished hole.
skip it if: you are drilling into case-hardened steel or need more than 5 bits per project — you will run out of spares quickly.
6. CaRoller 29Pcs Drill Bit Set, 135 Degree Tip High Speed Steel with Black and Gold Finish (1/16″-1/2″)
A 29-piece set from 1/16-inch to 1/2-inch that one buyer used to drill 30 holes in a steel I-beam with a single bit.
If you need a broad range of sizes rather than multiple copies of one size, this set covers every common diameter from 1/16-inch all the way up to 1/2-inch in 29 indexed steps. However, note that these are High Speed Steel bits with a black oxide finish — not cobalt — which means they are not as hard as M35 and will dull faster on stainless steel. The 135-degree split point helps with starting accuracy, and the full grinding and black oxide coating reduce friction.
A reviewer reported drilling 30 holes in a steel I-beam with one bit, though the bit showed significant wear by hole 30 with a chipped cutting edge — which is exactly the trade-off you get with HSS versus cobalt. Another buyer noted the bits are “excellent for mild steel, decent for stainless (just go slow and definitely used cutting oil).” The metal indexed case keeps every bit in its labeled spot, and the kit gives you both inch-fraction sizes from 1/16 to 1/2.
Full range on a budget: This is the set to buy if you are building a general workshop kit and will mostly drill mild steel, with only occasional stainless work — just plan to sharpen or replace bits after heavy use on hard metal.
Choose this for: a one-box solution for a job site or home shop where you need every bit size from tiny pilot holes up to a full half-inch.
Don’t choose this for: a dedicated stainless steel drilling project — you want the purity of M35 cobalt instead of HSS for prolonged hard metal work.
Understanding the Specs
M35 Cobalt vs. HSS
The “M35” marking on a drill bit means the steel contains 5% cobalt mixed into the high-speed steel. This addition lets the bit stay hard even when the cutting edge gets hot from friction against stainless steel. Plain HSS bits soften quickly at those temperatures, so you lose your edge after just a few holes. The letter “M” refers to a specific family of high-speed tool steels standardized by the AISI system, and the “35” indicates the nominal tungsten content — though for the buyer, the important part is the cobalt percentage.
135-Degree Split Point
A split point is a notch ground into the very tip of the bit that creates two cutting edges meeting at the center. When the point angle is 135 degrees instead of the standard 118 degrees, the bit has a flatter tip that bites into hard surfaces instead of sliding across them. This self-centering action means you can start a hole without a center punch and the bit will not walk or skate — especially important on stainless steel where a wandering tip can ruin the workpiece.
FAQ
Can you drill stainless steel with regular HSS drill bits?
Do I need cutting oil for stainless steel?
What does the 135-degree point do?
How many holes should a cobalt bit last in stainless steel?
Is a 3-flat shank better than a round shank?
Can I use a titanium-coated HSS bit instead of cobalt?
What RPM should I use for drilling stainless steel?
Will a 1/8-inch cobalt bit drill through a steel plate?
Final Thoughts: The Verdict
For most buyers, the bit for drilling stainless steel winner is the RCINDUS 20-Piece 3/16-inch M35 Cobalt Set because it gives you the right combination of 5% cobalt hardness, 135-degree split point accuracy, and enough spares to work through a project without downtime. If you need to drill large half-inch holes, grab the Narwhal 3-Pack 1/2-inch Cobalt Bits. And for a full workshop kit that handles everything from mild steel to occasional stainless, the CaRoller 29-Piece HSS Set covers every size from 1/16-inch to 1/2-inch.
How We Picked
We do not accept paid placement, and we did not hands-on test every unit. Instead, we match each pick to a real buyer and use-case by comparing the manufacturers’ published specifications against the patterns in verified customer reviews — so you get each pick’s real strengths and trade-offs instead of marketing copy.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of July 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.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply to the purchase of this product. As an Amazon Associate I earn from qualifying purchases.
CERTAIN CONTENT THAT APPEARS ON THIS SITE COMES FROM AMAZON. THIS CONTENT IS PROVIDED "AS IS" AND IS SUBJECT TO CHANGE OR REMOVAL AT ANY TIME.
Amazon and the Amazon logo are trademarks of Amazon.com, Inc. or its affiliates.