Best step drill bit

The Klein 25962 is my top pick because it covers the hole sizes most people need in one bit. Klein's product page lists 12 hole sizes from 3/16 to 7/8 in. (4.8 to 22.2 mm), in 1/16 in. steps.

That's every sixteenth from 3/16 up: 1/4, 5/16, 3/8, 7/16 and on to 7/8 in. If you need a hole for a 1/4 in. bolt, a 1/2 in. cable clamp or a 7/8 in. fitting, it's on this bit.

The shank is a 1/4 in. hex. Klein says it fits standard drills and impact drivers, so you don't need a chuck. That matters if your impact driver is the tool already on your belt.

Klein lists two spiral flutes that clear chips and help pull the bit through the material, and a titanium nitride coating it says helps shed heat for longer bit life.

The split point tip is there to start the hole without drifting when you add pressure. On thin sheet, a tip that stays put is what keeps the hole on your mark.

Each size is laser-etched on the bit. You read the number at the step, stop there, and you've got the hole you wanted.

Know the limit. Klein lists the 25962 for steel up to 16 gauge, plus wood, plastic and aluminum. The IRC's shield plate rule puts 16 gauge at 0.0575 in., so this is a thin sheet bit. For 1/8 in. stainless, look at the IRWIN or Bosch.

Klein's page also gives a height of 3.2 in. and a weight of 2.24 oz. It also carries Klein's warning to wear eye protection, which is good advice for every bit on this page.

My call: if you only buy one step bit, buy this one. It was sold by Amazon.com, new and in stock, on the day of the update.

The Klein 25960 picks up where the 25962 stops. Klein's product page lists three hole sizes, 7/8, 1-1/8 and 1-3/8 in. (22.2 to 34.9 mm). Each step is 1/4 in. bigger than the one before it.

The 1-3/8 in. step is why it's on this page. Delta's kitchen faucet spec sheet says its faucets mount on a standard 1-3/8 in. (35 mm) hole, plus or minus 1/8 in. Another Delta two-handle spec sheet lists 1-5/16 to 1-1/2 in. If you're adding a hole to a stainless sink deck, this is the size you'll drill.

Before you drill a sink, check the faucet's own spec sheet. Our kitchen faucet hole size guide walks through how to measure.

The build matches the 25962: two spiral flutes, a titanium nitride coating, a split point tip and a 1/4 in. hex shank for drills and impact drivers. The sizes are laser-etched at each step.

Klein lists the same limit too: steel up to 16 gauge, plus wood, plastic and aluminum. Klein doesn't list a stainless rating for this bit. If your sink is thicker than that, check before you start.

It's a bigger bit. Klein's page gives a height of 3.57 in. and a weight of 6.88 oz., about three times the 25962. On an impact driver, that weight sits out past the chuck, so hold the tool square to the work.

Its smallest step is 7/8 in., so it's no help for small holes. That's why it pairs with the 25962, which stops at exactly 7/8 in.

My call: the 25962 and 25960 are a pair. Buy both and you've got 3/16 to 1-3/8 in. on two hex shanks. It was sold by Amazon.com, new and in stock, on the day of the update.

The DEWALT DWA1790IR is three bits in one package: 1/8 to 1/2 in., 3/16 to 1/2 in. and 3/16 to 7/8 in. DEWALT's listing counts 31 hole sizes across the three.

The IR in the model number is DEWALT's impact ready line. The listing says these bits are optimized for impact drivers and work in rotary drills too. All three have a 1/4 in. hex shank.

Why three bits when one covers 3/16 to 7/8 in.? The small bits give you finer control. The 1/8 to 1/2 in. bit starts at 1/8 in., tied with NEIKO's 13 step bit for the smallest first step on this page. That's handy for small pilot holes.

Having two bits that both cut 3/16 to 1/2 in. sounds like waste. It isn't, if you drill a lot of small holes. When one dulls, you have a second, and you save the big bit's small steps for when you need them.

DEWALT lists a titanium nitride coated, two-flute spiral design for longer life and better chip removal. The tip is a split point, which DEWALT says increases speed. The step numbers are laser engraved.

The listing gives a 135 degree cutting angle and a weight of 4.96 oz. for the set.

What DEWALT doesn't list is a maximum material thickness. Without it, I'd treat these like the Klein bits and keep them to thin sheet. For 1/8 in. stock, the IRWIN and Bosch bits list that limit.

The set stops at 7/8 in. If you need a faucet hole, add the Klein 25960. Its first step is 7/8 in., right where the DEWALT set ends.

My call: for an impact driver owner who drills small holes every day, this is the set. It was sold by Amazon.com, new and in stock, on the day of the update.

The NEIKO 10197A is the widest range on this page in one box. NEIKO's listing gives the five bits: a 6 step (3/16 to 1/2 in.), a 13 step (1/8 to 1/2 in.), a 9 step (1/4 to 3/4 in.), a 10 step (1/4 to 1-3/8 in.) and a 12 step (3/16 to 7/8 in.).

Add those up and you get NEIKO's 50 sizes. But a lot of them repeat. All five bits start at 1/4 in. or smaller, so the small sizes show up again and again. The real range is 1/8 to 1-3/8 in., and the 10 step bit is the one that reaches the faucet size.

The shanks split two ways. The 6 step and 13 step bits have 1/4 in. shanks, and the other three have 3/8 in. shanks. NEIKO calls them tri-flatted, for a secure fit in a chuck. They aren't hex, so the 3/8 in. bits need a drill chuck.

NEIKO lists high-speed steel with a titanium coating and a two-flute design. It says the two flutes deburr while drilling and let chips escape. The listing also says the set doubles as a hole expander, which is handy for opening a hole that's already there.

The materials NEIKO names are plastic, aluminum, copper, stainless steel and other sheet metal. It doesn't give a thickness limit, so I'd keep it to thin sheet like the Klein and DEWALT bits.

One thing doesn't add up in the listing. The case line says four bits, but the size list names five, and the photo shows five. I went by the size list.

The set ships in a red blow-mold case. With five bits, the case is what keeps you from losing the one size you need.

My call: if you want one case that covers every size up to a faucet hole, this is it. It was sold by Amazon.com, new and in stock, on the day of the update.

Unibit is IRWIN's name for its step bits, and the #3 is the 1/4 to 3/4 in. model. The listing gives nine sizes from 1/4 to 3/4 in., in 1/16 in. steps, on a 3/8 in. 3-flatted shank.

It's my pick for stainless, copper and brass because IRWIN names those metals and gives a limit. The listing calls it ideal for thin materials, including stainless steel, copper, brass, aluminum, plastic and laminates, and gives a maximum material thickness of 1/8 in.

The big difference is the flute. Every other bit on this page has two flutes. IRWIN uses a single flute, patented, which it says gives a true round hole every time and more control through the steps.

Why would one flute help? IRWIN doesn't say beyond control and roundness. What I can tell you is that it's the only single-flute bit here, so if a two-flute bit is leaving you out-of-round holes in thin sheet, this is the one to try.

The tip is IRWIN's SpeedPoint. The listing says it penetrates faster than earlier Unibits and prevents walking, so the bit starts where you put it.

IRWIN says the 3-flatted shank prevents slipping in the drill chuck. There's no hex version of this model, so it won't drop into an impact driver.

The sizes are laser-etched inside the flute, per the listing, where they're out of the way of the cutting edges. The bit weighs 2.08 oz.

Know its limit on size too. At 3/4 in., it stops short of the 7/8 in. knockout size and well short of a faucet hole. It's a precise small-hole bit, not a do-everything bit.

My call: for clean holes in thin stainless or copper, this is the bit. It was sold by Amazon.com, new and in stock, on the day of the update.

The Bosch IMSDC002 is two bits: 3/16 to 7/8 in. and 1/4 to 1-1/8 in., per Bosch's step bit family page. That's the furthest any hex-shank pick here reaches except the Klein 25960. The two bits overlap from 1/4 to 7/8 in., so you can save the bigger bit for the bigger holes.

The listing names who it's for. It says the bits are ideal for electrical, plumbing and HVAC contractors, for knockouts, conduit and faucet installations, in materials up to 1/8 in. thick.

One caution on that faucet line: the top step is 1-1/8 in. That's short of the 1-3/8 in. hole Delta calls standard for kitchen faucets. For a faucet hole, you'll still want a bit that reaches 1-3/8 in.

The shank is Bosch's Impact Tough hex. The listing says the bits are optimized for impact drivers and also fit drill/drivers, in high or low speed mode on a cordless drill.

Bosch lists two cutting edges and says that makes them cut twice as fast through tough material. It also lists a balanced double flute that it says cuts chatter and vibration, and burr-free holes. I can't check the twice-as-fast claim from a listing, so I'm only passing on what Bosch says.

The materials list is the longest here: sheet metal, ducts, steel, copper, brass, aluminum, plastic, vinyl siding, plasterboard, PVC, stainless steel and cast iron. Bosch is the only maker on this page to name cast iron.

The bits are Swiss made, the listing says. Bosch doesn't list the number of steps on each bit, so I marked that as not listed.

My call: if you run an impact driver and drill conduit or knockout holes up to 1-1/8 in., this is the set. It was sold by Amazon.com, new and in stock, on the day of the update.

The Greenlee GSB12 has the thickest metal rating on this page. Greenlee's product page lists a maximum sheet metal thickness of 10 gauge (3.5 mm). That's more than the 1/8 in. IRWIN and Bosch list, and more than double Klein's 16 gauge.

Greenlee names mild steel, aluminum, brass, copper, wood, fiberglass, plastics and laminates. It doesn't name stainless. The top step is 1-3/8 in., which is the faucet hole size.

Now the honest part. Greenlee's spec table lists four drill stages, with a minimum diameter of 3/16 in. and a maximum of 1/8 in. A maximum smaller than the minimum can't be right, and the bit is sold as a 1-3/8 in. bit. I couldn't confirm the in-between steps, so I marked them not listed.

Greenlee calls its patented split-step design the reason it cuts fast and smooth, with more holes per battery charge. It also lists progressive cutting edges, which it says balance aggression to use torque well and keep the drill from stalling.

The rest of the build: a split point tip, an improved double flute for chip clearing, laser markings for size, and a three-flat shank that fits all 1/2 in. drill chucks. There's no hex shank, so this one goes in a drill.

The GSB12 replaced Greenlee's older 36414, and it's also sold in a carton of 25 as the GSB12-B. The Amazon listing gives a 1 year warranty and a steam oxide finish.

My call: for 1-3/8 in. holes in sheet thicker than the other bits allow, this is the one. Greenlee links a datasheet, MA6957, for its GSB series. Check the steps there if you need a specific size below that. It was sold by Amazon.com, new and in stock, on the day of the update.