Cobalt vs Titanium Drill Bits vs Black Oxide: What Each Buys

What does the color of a drill bit tell you?

The color of a drill bit tells you the finish, not the steel. Gold usually means a titanium nitride (TiN) coating. Black means black oxide. Bronze, on a Triumph bit, means cobalt. A black bit with a gold tip is black and gold, which is not titanium at all. Only one of these, cobalt, changes the metal the bit is made of. The rest are surface treatments on the same high-speed steel.

Store prices on Nov 4, 2026. Every drill bit here is priced per bit and sold by the sleeve.

Cobalt vs titanium vs black oxide drill bits: what is each one?

A cobalt drill bit is a different alloy. A titanium drill bit and a black oxide drill bit are the same M2 high-speed steel with different surface treatments. That one fact decides everything below: where the advantage lives, what happens when you sharpen the bit, and what you should pay for it.

Verdict: Buy by the metal, not the color. Stainless or anything a file barely bites: cobalt. A run of holes in mild steel or cast iron with no resharpening: titanium. Everything else, and anything you sharpen: black oxide or black and gold, and spend the difference on a sleeve of the right size.

Five things you will read online about cobalt vs titanium drill bits that are wrong:

• "Milwaukee Thunderbolt bits are cobalt." They are black oxide. Milwaukee's cobalt line is Red Helix.

• "Coated bits cannot be resharpened." They can. You lose the coating at the edge and keep an HSS bit.

• "Black oxide is made by heating the bit to 950°F." It is a chemical conversion bath. The finish does not change the steel's hardness.

• "Galvanizing is highly abrasive." Zinc is soft. It gums the flutes; it does not wear the edge.

• "Titanium bits last 3 to 6 times longer than HSS." No one publishes the test. The coating helps in mild steel and cast iron, and the first resharpen removes it.

Which drill bit coating for which metal?

For mild steel, buy a black and gold HSS bit: at 1/4 in. that is 012516 at $3.24, sleeve of 12. For stainless steel, buy cobalt: 013516 at $7.80, sleeve of 12. Every other metal fits one of the rows below. Prices are for 1/4 in.; the size table further down covers the rest.

Point angle, length and the two-diameters flute rule are covered in How to Choose Drill Bits for Metal. This guide only decides the coating.

What does cobalt cost over titanium and black oxide, size by size?

A cobalt bit costs 2.0 to 2.4 times a black and gold bit of the same size, and a titanium bit costs 1.6 to 1.9 times. The multiple holds from 1/16 in. to 1/2 in. The table is our store price per bit on Nov 4, 2026, for the five finishes we sell in jobber length.

Triumph Twist Drill, made in the USA. Bright 0110xx, black oxide HD 0114xx, black and gold ThunderBit 0125xx, TiN ThunderBit 0128xx, Cobalt ThunderBit 0135xx; the last two digits are the size in 64ths. Minimum order is a sleeve of 12 up to 1/4 in. and 6 above it for black and gold, TiN and cobalt; 24 or 36 for bright and black oxide at small sizes.

The sleeve changes the answer more than the price per bit does. At 1/4 in., the black oxide bit is cheaper per bit ($2.60) but its minimum is 24, so the sleeve is $62.40. The black and gold ThunderBit is $3.24 with a minimum of 12, so the sleeve is $38.88. The cheapest way to get 1/4 in. bits in the door is the black and gold sleeve. The cobalt sleeve of 12 is $93.60 and the TiN sleeve is $68.16.

Browse every size and finish in the jobber length collection.

Is a cobalt drill bit worth the money?

A cobalt drill bit is worth the money when it drills stainless steel or any steel that heats the edge, because there it outlasts the $3.24 bit by far more than the 2.4 times it needs to. In mild steel it is not worth it. The black and gold bit never gets hot enough for the cobalt to matter, so you pay 2.4 times for nothing.

The math is simple. At 1/4 in., cobalt costs $7.80 and black and gold costs $3.24. Cobalt has to make 2.4 times as many holes to cost the same per hole. In 304 stainless, a plain HSS bit may stop cutting after a few holes and a cobalt bit keeps going, so cobalt wins easily. In angle iron, both bits make many holes and the cheaper one wins.

What our trade customers buy says the same thing. In the last 12 months they bought 5,472 black and gold jobber bits on account, 24 cobalt bits and no TiN bits. Our single best-selling drill bit is a 1/8 in. black oxide stubby, CD30008 at $1.76, bought 4,920 at a time by a production shop. Shops that drill thousands of holes buy the cheapest 135° split point and treat it as a consumable. Coatings sell to people drilling a few holes in something hard.

So buy cobalt by the size you drill in stainless, not as a set. A 29-piece cobalt set costs a lot of money for 25 sizes you will not use in stainless. One sleeve of the right size costs less and covers a year of work.

Why does a titanium drill bit go dull after a few holes in stainless steel?

A titanium drill bit goes dull in stainless steel because the coating is only on the surface and stainless heats the cutting edge faster than any mild steel. Once the TiN wears off the tip, the bit is plain high-speed steel, and plain HSS loses its hardness at the temperature stainless makes. Then the bit rubs instead of cutting, the rubbing work-hardens the hole, and the next hole is harder still. Cobalt keeps its hardness at that heat, which is the whole reason it exists.

Speed does most of the damage. A cordless drill in high gear runs about 1,800 RPM. A 1/4 in. bit in stainless wants about 600 RPM. The full table by size and metal is in our drill speed chart; these four rows are from it.

Three rules keep any of these bits alive in stainless: drop the drill to low gear, push hard enough to make a curled chip, and use cutting oil on every hole. A blue chip or a squeal means the edge is already too hot. No coating fixes a bit that was run at three times its speed.

Can you sharpen cobalt and titanium drill bits?

Yes, you can sharpen cobalt, titanium and black oxide drill bits on a bench grinder or a drill sharpener. What you get back is different. A sharpened cobalt bit is the same bit, because the cobalt is in the steel. A sharpened titanium bit is a plain M2 high-speed steel bit, because the coating is gone from the new edge. A sharpened black oxide bit is also plain HSS at the edge, and it lost nothing that mattered, since the finish never cut anything.

That is why cobalt makes sense for a shop that sharpens, and titanium makes sense for a crew that throws bits away. If you resharpen, the extra $2.44 for TiN at 1/4 in. buys you the first life of the bit only.

Stubby or jobber: does the length change which coating you buy?

The length does not change the coating choice, but it changes what we can sell you. Every cobalt and titanium bit we stock is jobber length. Stubby bits, also called screw machine length, come in black oxide and black and gold only. Our mechanics length bits sit between the two and have a 3-flat shank that will not spin in a keyless chuck.

Pick the stubby for sheet metal, duct, panels and anywhere the drill has no room. A short bit flexes less, so it walks less and snaps less in thin stock. For stainless duct or an enclosure, where you want cobalt but need a short tool, use the cobalt jobber in a drill, or a cobalt step bit for knockouts; our step drill guide for stainless covers those. Holes over 1/2 in. in plate move to a Silver and Deming bit. Browse the stubby and mechanics length collection.

Who makes the best cobalt drill bits?

The best cobalt drill bits for a trade shop are solid cobalt high-speed steel with a 135° split point, sold by the size you need rather than as a set. Ours are made by Triumph Twist Drill in the USA: the Cobalt ThunderBit, 29 sizes from 1/16 to 1/2 in., $2.64 to $27.07 a bit, in sleeves of 12 or 6. Our Cobalt ThunderBit is [[PLACEHOLDER: M35 or M42, confirm the grade with Triumph]] cobalt steel.

The brands you see in a big box store are not different kinds of cobalt. Milwaukee Red Helix, DeWalt Industrial Cobalt, Bosch and Drill America cobalt bits are all M35 or M42 alloy. The differences are the point grind, the web thickness and the price per bit. The two things to check on any cobalt bit are the stamp on the shank (M35, M42 or Co) and whether it is sold in the size you drill.

If you want one set that covers everything but stainless, the 29-piece ThunderBit+ 3-flat set is black and gold HSS in every fractional size to 1/2 in. for $164.40. Add cobalt in the two or three sizes you drill in stainless and you are set.

For the whole family of twist, masonry, tile and hole-making bits, see Types of Drill Bits Explained. Questions about a job? Call our team at (833) 4-ETOOLS or email sales@eldoradotools.com.

Draft prepared Nov 4, 2026. Prices checked on the store that day.