Best Drill Bit for Metal Studs (2026): Picks, Sizes & How to Drill
2026-09-05
Best Drill Bit for Metal Studs (2026): Picks, Sizes & How to Drill
The short answer
The best drill bit for metal studs is a 5% cobalt (M35) twist drill bit with a 135° split point. It stays sharp in the thin, hard, galvanized steel that framing studs are made from, and the split point keeps the bit from walking across the curved stud web. For the 25-gauge studs used in most interior drywall partitions, a 1/8-inch (3.2 mm) cobalt bit handles the majority of jobs — cabinet mounting, brackets, outlet boxes and anchors.
Whether you are a framer, electrician, plumber, cabinet installer or a serious DIYer, drilling through metal studs (also called steel studs, drywall studs or cold-formed steel framing) is a daily task — and it destroys the wrong drill bit in seconds. This guide tells you exactly which drill bit to buy, what size to use for each screw, and how to drill a clean hole in 25-gauge to 16-gauge steel studs without burning up your bits.
Metal studs are not solid steel blocks. They are cold-formed steel (CFS) framing members — thin galvanized sheet steel roll-formed into a C-shape with a web and two flanges. That geometry is exactly what wears out drill bits:
Thin, curved web. The web is typically 18 to 68 mils thick (0.018–0.068 inch). A sharp point quickly penetrates, but the curved surface gives the bit nothing flat to bite into, so it wanders and grabs.
Galvanized coating. The zinc coating is abrasive and generates friction and heat as soon as the bit touches it.
Concentrated heat. With so little material in contact, heat builds fast. Standard high-speed steel (HSS) bits lose their temper (soften) when they overheat and dull almost instantly.
Flange edges. Drilling near the flange edge means the bit cuts on an angle through the corner, which is the fastest way to snap a brittle bit.
The solution is not brute force. It is the right bit material, the right point geometry, and the right technique — all covered below.
Metal stud gauges at a glance
Before choosing a bit, know what you are drilling. Steel stud thickness is expressed in gauge, and here is the part that confuses most people: the lower the gauge number, the thicker the steel. The chart below shows the standard thickness values used in cold-formed steel framing.
Data basis: standard cold-formed steel framing thicknesses (25–14 gauge, 18–68 mil) as used in ASTM C955 / C645 framing specifications.
Practical takeaway: Most interior, non-load-bearing walls use 25-gauge studs (≈18 mil), which any sharp HSS or cobalt bit drills with ease. Structural walls, shaft walls and exterior walls use 20-gauge and heavier (33 mil and up) — that is where cobalt or carbide really pays for itself.
Drill bit types compared for steel studs
Every drill bit is not the same. Here is how the common types stack up when the target is galvanized steel framing:
Drill bit types for metal studs
Bit type
Best for
Pros
Cons
Verdict for metal studs
Standard HSS
Mild steel, occasional 25-ga studs
Cheap, readily available
Softens fast on galvanized steel; dulls quickly
OK for a few holes on thin studs; keep spares
Black-oxide HSS
General metal drilling
Slightly better heat resistance, resists rust
Still HSS at the core; not for heavy use
Good budget choice for light DIY
Titanium-coated (TiN)
Mild steel and aluminum
Coating adds hardness and lubrication
Coating wears off on hard/abrasive steel; no coating left = plain HSS
Not recommended for steel studs
Cobalt M35 (5% cobalt)
Steel studs (25–18 ga), stainless steel
Cobalt alloyed through the whole bit; holds hardness when hot; long life
Cuts burr-light holes in thin steel; self-centering; one bit = many sizes
Not for deep holes; expensive if damaged
Best for 1/2–1 in penetrations
Two details matter more than brand: point geometry and cobalt content. A 135° split point self-centers on the curved stud web and prevents walking, while a standard 118° point wanders and skips. Cobalt content (M35/M42) is alloyed through the bit, so the hardness is not a surface coating that can wear off — this is why professional framers and electricians standardize on cobalt for steel studs.
Best drill bits for metal studs by scenario
Recommended picks for 2026
Scenario
Recommended bit
Why
Best overall (one set for everything)
M35 cobalt twist-drill set, 1/16–1/4 in (29-piece class sets from Irwin, Milwaukee or DeWalt)
Irwin’s 29-piece M35 cobalt set was rated the best overall drill bit set for stainless steel in hands-on 2026 testing; the same hardness carries through to galvanized studs
Best budget (occasional DIY on 25-ga studs)
Black-oxide HSS set with 135° split points
Cheap and good enough for a handful of holes in thin interior studs
Best for structural studs (18–16 ga)
M42 (8% cobalt) bits, or carbide-tipped for hardened steel
Thicker steel generates more heat; M42 keeps its edge where M35 and HSS fade
Best for conduit, cable & pipe penetrations
Step drill bit (unibit), 1/8–3/4 in or 1/8–1 in
Clean, round, burr-light holes in thin steel without grabbing; matches common knockout sizes
Best single bit to keep in your pouch
1/8 in (3.2 mm) M35 cobalt, 135° split point
The exact pilot-hole size for #8 screws — the most common screw in metal stud work
Note on brands: Irwin, Milwaukee, DeWalt, Bosch and Lenox all make M35/M42 cobalt bits that perform well. What separates them in practice is the point geometry and how consistently the set sizes are manufactured — buy from a reputable brand and replace bits as soon as they start grabbing.
What size drill bit for metal studs (pilot-hole chart)
When you drive a self-tapping sheet-metal screw into a steel stud, the pilot hole should be close to the screw’s root (minor) diameter, not the thread diameter. Too small, and the screw snaps or the stud distorts; too large, and the threads have nothing to bite. For 25- to 20-gauge studs, this chart is what most framers use:
Pilot-hole drill sizes for self-tapping screws in metal studs
Screw size
Pilot bit — 25–20 ga studs
Pilot bit — 18 ga and heavier
Typical use
#6
7/64 in (2.8 mm)
1/8 in (3.2 mm)
Light trim, electrical straps
#8
1/8 in (3.2 mm)
9/64 in (3.6 mm)
Most common: brackets, boxes, tracks
#10
9/64 in (3.6 mm)
5/32 in (4.0 mm)
Heavier brackets, door hardware
#12
5/32 in (4.0 mm)
11/64 in (4.4 mm)
Structural connections, heavy hangers
Two exceptions worth knowing: (1) TEK (self-drilling) screws with a drill-point tip make their own hole in 25- to 20-gauge studs — no pilot hole needed. (2) For toggles and anchors (e.g., a 1/4-in toggle bolt), drill the hole the anchor body specifies, typically 1/2 in for standard toggles.
How to drill a metal stud, step by step
1
Mark and center-punch
Measure twice, mark the hole, then hit a center punch hard enough to leave a dimple. This gives the split point something to seat into and stops the bit from skating down the curved web.
2
Pick the bit and the speed
Use a cobalt bit sized to your screw (see the chart above). Run a cordless drill/driver on its low-speed, high-torque setting — roughly 500–1,000 RPM for bits up to 1/4 in. High speed on thin steel burns bits and smears the metal.
3
Lubricate the point
Dip the tip in cutting oil, or use WD-40 or 3-in-1 oil. Lubricant removes heat and extends bit life dramatically on galvanized steel. Reapply for deeper or larger holes.
4
Drill with firm, steady pressure
Keep the drill perpendicular to the web. Let the bit do the cutting — steady pressure, not force. If the bit starts smoking or turning blue, you are going too fast: stop, oil, and slow down.
5
Clear the chips
Thin studs cut fast. Withdraw the bit briefly on deeper penetrations so chips clear the flutes; packed chips cause the bit to grab and snap.
6
Deburr the hole
Remove the sharp burr on both faces with a deburring tool or a slightly larger bit run by hand. Burrs catch drywall, strip screw threads, and — on cable runs — can cut wire insulation.
7
Protect wires and pipes
When you drill studs for cable or conduit, install plastic grommets or bushings in every hole. Sharp-edged steel studs are a classic source of short circuits and pipe damage.
Pro tips for clean holes every time
Never use a wood or masonry bit on a metal stud. A wood bit will grab and snap; a masonry bit is too brittle and dulls immediately.
Drill from the finished side. The entry side gets the cleaner hole; the exit side gets the burr. If the burr side faces into the wall cavity, deburr it anyway.
Replace bits when they grab. A dull cobalt bit costs more than the screw it destroys. Sharpening cobalt is possible with a proper grinder, but replacement is often cheaper for 1/8-in bits.
Batch your drilling. For many holes (rack installations, whole walls), set up a drill guide or mark all holes first — the bit stays cooler and the layout is more accurate.
Match the drill to the anchor. Read the anchor or toggle package for its required hole size; it overrides the screw chart above.
Frequently asked questions
What is the best drill bit for metal studs?
The best drill bit for metal studs is a 5% cobalt (M35) twist drill bit with a 135° split point. It stays sharp in the galvanized steel used for framing studs, and the split point stops the bit from walking on the curved stud web. For 25-gauge interior studs, a 1/8-inch (3.2 mm) M35 bit handles most jobs.
Do I need a pilot hole before driving screws into metal studs?
Yes, for standard self-tapping sheet-metal screws you should drill a pilot hole that matches the screw’s root diameter so the threads can bite without the screw snapping or distorting the stud. Self-drilling TEK screws with a drill-point tip are the exception: in 25- to 20-gauge studs they form their own hole and need no pilot.
Are cobalt drill bits better than titanium bits for steel studs?
For steel studs, yes. Cobalt is alloyed through the entire bit (M35 = 5% cobalt, M42 = 8% cobalt), so it keeps its hardness even when the cut gets hot. Titanium bits only carry a surface coating that wears off on hard or galvanized steel. Cobalt is the standard recommendation for drilling steel studs and stainless steel.
What size drill bit do I need for #8 screws in a metal stud?
Use a 1/8-inch (3.2 mm) drill bit for #8 self-tapping screws in 25- to 20-gauge metal studs. On 18-gauge and heavier structural studs, step up to 9/64-inch (3.6 mm) so the screw does not snap in the harder steel.
Can I use a step drill bit on metal studs?
Yes. Step drill bits (unibits) are the best choice for larger penetrations in metal studs, such as running conduit, cable or plumbing. They cut clean, burr-light holes and enlarge an existing pilot hole without grabbing, which makes them ideal for 1/2-inch to 1-inch penetrations.
Do self-drilling (TEK) screws work in metal studs without a pilot hole?
Yes. TEK screws have a built-in drill-point tip that drills and taps in one step, and in 25- to 20-gauge studs they need no pilot hole. In 18-gauge and heavier structural steel, use a low-speed drill and let the screw’s point do the cutting; for thick or hardened steel, a pilot hole is still safer.
Final verdict
Buy a quality M35 cobalt set with 135° split points and you are covered for nearly every metal stud job. Keep a 1/8-inch cobalt bit as your go-to for #8 screws, add a step drill bit for conduit and cable penetrations, and pair everything with slow speed, cutting oil and a center punch. That combination drills clean holes in 25-gauge to 16-gauge studs, protects your bits, and protects the wires that run through them.
How this guide was built: Recommendations are based on cold-formed steel framing thickness standards (25–14 gauge, 18–68 mil), drill-bit metallurgy (HSS, M35 and M42 cobalt, carbide), standard tapping-screw pilot-hole sizing practice, and 2026 hands-on drill bit roundups in the trade press. Sizes and thicknesses are given in imperial with metric equivalents.
