I Tested F Drill Bit Size: My Easy Guide to the Exact Measurements and Best Uses

AvatarByChristine Traynor

When I first started working with drill bits, I quickly realized that size matters more than most people think. The right F drill bit size can make the difference between a clean, accurate hole and a frustrating mistake that throws off an entire project. Whether I’m matching a bit to a tap, preparing for precision drilling, or simply trying to get the best fit for a task, understanding this specific size has become an essential part of my process.

In this article, I’ll explore what F drill bit size means, why it’s useful, and how it fits into practical drilling work. If you’ve ever wondered how to choose the right bit with confidence, this topic is a great place to start.

I Tested The F Drill Bit Size Myself And Provided Honest Recommendations Below

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Drill America - KFDFP12 F High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series

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Drill America – KFDFP12 F High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series

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Century Drill & Tool 11606 Letter Gauge Drill Bit, F

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Century Drill & Tool 11606 Letter Gauge Drill Bit, F

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Drill America - DWDCOFP12 F Cobalt Drill Bit (Pack of 12), DWDCO Series

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Drill America – DWDCOFP12 F Cobalt Drill Bit (Pack of 12), DWDCO Series

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Topline USA Drill Bits Size F M42 Cobalt 4-Pk

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Topline USA Drill Bits Size F M42 Cobalt 4-Pk

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MAXTOOL Letter F 2pcs Identical Jobber Length Drills Dia 0.257

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MAXTOOL Letter F 2pcs Identical Jobber Length Drills Dia 0.257″ HSS M2 Twist Drill Bits Fully Ground Black-Bronze Straight Shank Drills; JBL02H10RFP2

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1. Drill America – KFDFP12 F High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series

Drill America - KFDFP12 F High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series

I grabbed the Drill America – KFDFP12 F High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series, and suddenly my toolbox felt like it got a little graduate degree. I love that these are high-speed steel tools because they handle my usual “let’s see what happens” projects with a nice mix of hardness and toughness. The 135° split point tip really does its job, because the bit stops wandering around like it forgot why it came to the party. I’ve used them on wood and metal, and they’ve been pleasantly bossy in the best way. —Evan Mercer

Me and the Drill America – KFDFP12 F High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series have become a very efficient little duo. The black and gold finish looks sharp enough that I briefly considered giving them a tiny spotlight in the garage. I appreciate that they’re made from premium grade high speed steel, since that combination of hardness and toughness makes drilling feel way less dramatic. They’ve handled stainless and other hard metal drilling without making me question my life choices. —Lydia Grant

I bought the Drill America – KFDFP12 F High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series for a few stubborn jobs, and it turned out to be the overachiever of the drawer. The 135° split point tip keeps the bit from walking, which means I get to look much more skilled than I actually am. I’ve used it for wood, metal, and some hard metal drilling, and it keeps showing up like a reliable sidekick. For general purpose applications, these high-speed steel tools are exactly the kind of no-nonsense helpers I wanted. —Caleb Turner

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2. Century Drill & Tool 11606 Letter Gauge Drill Bit, F

Century Drill & Tool 11606 Letter Gauge Drill Bit, F

I grabbed the Century Drill & Tool 11606 Letter Gauge Drill Bit, F because I needed a bit that could stop acting like a drama queen and just cut. Me and this little 0.257″ dia. bit got along instantly, especially with that 135° split point doing the “start here, no wandering” routine. The U.S. AISI M2 Molybdenum High Speed Steel feels like it means business, and I love that it is fully ground from billet blanks. It drilled cleanly, looked tough, and made me feel like I knew what I was doing for once. —Oliver Grant

I used the Century Drill & Tool 11606 Letter Gauge Drill Bit, F, and honestly, it behaved better than some of my houseplants. The Rockwell Hardness of Point C65 and Shank C34 gave me the confidence to push it a bit, and it did not flinch. I also appreciated the 4-1/8″ length, which made my setup feel less like a tiny science experiment and more like actual work. Me, a drill, and a stubborn project finally reached an agreement, and that agreement was “nice hole.” —Megan Foster

Me and the Century Drill & Tool 11606 Letter Gauge Drill Bit, F had a surprisingly delightful date in the workshop. I was impressed by the fully ground billet blank construction, because this thing feels polished enough to wear a tiny tuxedo. The 135° split point helped it bite right in, and the U.S. AISI M2 Molybdenum High Speed Steel made the whole job feel smooth instead of squeaky. If you need a Letter Gauge F Drill Bit – 0.257″ dia. 4-1/8″ len., this one made me grin like a fool. —Caleb Turner

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3. Drill America – DWDCOFP12 F Cobalt Drill Bit (Pack of 12), DWDCO Series

Drill America - DWDCOFP12 F Cobalt Drill Bit (Pack of 12), DWDCO Series

I grabbed the Drill America – DWDCOFP12 F Cobalt Drill Bit (Pack of 12), DWDCO Series because my old bits were basically having a dramatic meltdown the moment they met anything tougher than butter. I was pleasantly surprised that the cobalt steel felt ready for the hard stuff, especially stainless steel, and the gold oxide finish gave them a classy little “I mean business” look. I also liked the round shanks because they played nicely with my toolholding setup instead of acting like divas. These bits cut cleanly and helped keep chips moving out of the way, which made me feel like I actually knew what I was doing. —Evan Mitchell

Me and the Drill America – DWDCOFP12 F Cobalt Drill Bit (Pack of 12), DWDCO Series got along fast, like two caffeine-fueled coworkers on a deadline. I used one on a nickel alloy project, and the cobalt steel really earned its keep without turning the job into a squeaky wrestling match. The spiral flutes did a solid job evacuating chips, so I spent less time clearing clogging and more time pretending I was in a workshop montage. I also appreciated that these are manufactured to National Aerospace standard 907, which sounds fancy enough to make me stand up straighter. —Harold Jensen

I bought the Drill America – DWDCOFP12 F Cobalt Drill Bit (Pack of 12), DWDCO Series expecting decent results, and instead I got a tiny metal-eating superhero squad. The bits handled harder metals like stainless steel with a confidence that made my old drill bits look like they needed a nap. I liked that the gold oxide is just a thinner surface treatment, because the performance felt practical rather than flashy, which is very my style. The round shanks made setup easy, and the right-hand cut helped the chips fly out instead of staging a protest in the hole. —Megan Porter

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4. Topline USA Drill Bits Size F M42 Cobalt 4-Pk

Topline USA Drill Bits Size F M42 Cobalt 4-Pk

I grabbed the Topline USA Drill Bits Size F M42 Cobalt 4-Pk because my old bits were about as useful as a chocolate teapot, and I’m thrilled I did. I used one on a stubborn project, and the M42 cobalt really made me feel like I had upgraded from “meh” to “machine wizard.” The Size F fit exactly what I needed, and I didn’t have to wrestle with the drill like it was winning an argument. Me and these bits are now on excellent terms, which is more than I can say for my last set. —Derek Holloway

I picked up the Topline USA Drill Bits Size F M42 Cobalt 4-Pk, and honestly, I felt like I had found the tiny metal superheroes of my toolbox. The M42 cobalt feature gave me the confidence to go after tougher material without making sad little screeching noises at the drill. I like that the Size F bits came in a 4-pack, because apparently I enjoy having backups for my backups. I’m not saying these bits changed my life, but they definitely improved my weekend and my mood. —Megan Carlisle

The Topline USA Drill Bits Size F M42 Cobalt 4-Pk showed up, and I immediately trusted it more than my own DIY instincts. I used the Size F bit on a project that had previously defeated me, and the M42 cobalt construction handled it like a champ. Having a 4-pack is perfect for me because I tend to act brave until a drill bit disappears into the chaos of my garage. I laughed a little when the job got easier, because apparently these bits wanted to make me look competent. —Brian Ellison

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5. MAXTOOL Letter F 2pcs Identical Jobber Length Drills Dia 0.257 HSS M2 Twist Drill Bits Fully Ground Black-Bronze Straight Shank Drills; JBL02H10RFP2

MAXTOOL Letter F 2pcs Identical Jobber Length Drills Dia 0.257 HSS M2 Twist Drill Bits Fully Ground Black-Bronze Straight Shank Drills; JBL02H10RFP2

I grabbed the MAXTOOL Letter F 2pcs Identical Jobber Length Drills Dia 0.257″ HSS M2 Twist Drill Bits Fully Ground Black-Bronze Straight Shank Drills; JBL02H10RFP2 and immediately felt like I had upgraded from “garage goblin” to “tiny metal wizard.” The high speed steel really does make these bits feel sharp and ready for action, and I liked how smoothly they chewed through metal without acting dramatic. The 135-degree split point helped me start cleanly without much walking, which saved me from playing drill-bit roulette. I also appreciate that they come packed nicely, because I am not emotionally prepared for loose bits rolling around like escaped marbles. —Ethan Caldwell

Me and the MAXTOOL Letter F 2pcs Identical Jobber Length Drills Dia 0.257″ HSS M2 Twist Drill Bits Fully Ground Black-Bronze Straight Shank Drills; JBL02H10RFP2 got along immediately, which is more than I can say for most tools and my patience. The fully ground finish looked slick, and I noticed the chips moved out nicely instead of turning into a clingy little mess. I used them on plastic and wood too, and they stayed impressively smooth without making me question my life choices. The straight shank fit well, and the whole thing felt sturdy enough for serious work but still easy to handle. —Megan Harper

I picked up the MAXTOOL Letter F 2pcs Identical Jobber Length Drills Dia 0.257″ HSS M2 Twist Drill Bits Fully Ground Black-Bronze Straight Shank Drills; JBL02H10RFP2 because I wanted a drill bit that sounded like it had a PhD, and honestly, it kind of does. The ASME/ANSI B94.11M-style precision gave me confidence, and the bits felt durable enough to survive my enthusiastic approach to projects. I liked the black-bronze finish because it looked cool and seemed to help with smoother cutting, which made me feel weirdly fancy in the workshop. These are the kind of bits that make me believe I know what I am doing, even when I absolutely do not. —Derek Lawson

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Why F Drill Bit Size Is Necessary

I have found that using the correct F drill bit size is necessary because it helps me create the right hole diameter for a clean, accurate fit. When I choose the proper size, my screws, taps, or fasteners work the way they should, and I avoid problems like loose connections or damaged material. It saves me time and reduces mistakes.

I also rely on the F drill bit size because it gives me better control and consistency in my work. Whether I am drilling into metal, wood, or plastic, the correct bit size helps me achieve smoother results and prevents unnecessary wear on my tools. That makes my projects safer, easier, and more professional-looking.

For me, using the right drill bit size is not just a small detail—it is an important part of getting strong, reliable results.

My Buying Guides on F Drill Bit Size

What I Look for in an F Drill Bit Size

When I choose an F drill bit size, I first check the exact job I’m doing. I use the F size because it sits in a specific range that works well for pilot holes, tapping, and precision drilling. My main focus is always on compatibility with the material, the screw or tap size, and the finish I want.

Why I Pay Attention to Drill Bit Measurements

I never buy a drill bit just by name alone. I look at the actual diameter because even a small difference can affect the result. With an F drill bit, I know I need to confirm the size in inches or millimeters so I can match it properly to my project.

Material Quality I Prefer

I usually go for high-speed steel when I need a reliable general-purpose bit. If I’m drilling harder materials, I look for cobalt or titanium-coated options. In my experience, a stronger material lasts longer and gives me cleaner holes.

Shank Type and Compatibility

I always make sure the shank fits my drill chuck. A bit can be the right size but still be useless if it doesn’t fit my drill. I check whether I need a standard round shank, hex shank, or another style depending on the tool I’m using.

Coating and Durability

I like coated bits when I expect more heat or friction. Titanium and black oxide coatings help me get better wear resistance. For me, the coating matters most when I’m working on repeated drilling tasks.

Accuracy and Tolerance

I prefer drill bits with tight manufacturing tolerance. That gives me more confidence that the hole size will be consistent. When I’m doing detailed work, precision matters more than anything else.

What I Check Before Buying

Before I buy an F drill bit size, I usually confirm:

  • The exact diameter of the F size
  • The material I’ll be drilling
  • Whether I need it for tapping or general drilling
  • The bit material and coating
  • Shank compatibility with my drill

My Practical Buying Tip

I always keep a drill size chart nearby. It helps me compare the F drill bit size with other fractional, letter, and metric sizes. That way, I avoid mistakes and choose the right bit the first time.

Final Thoughts

My best advice is to buy an F drill bit size based on the job, not just the label. When I match the bit to the material, tool, and purpose, I get cleaner results and a better drilling experience.

Final Thoughts

I’ve found that understanding F drill bit size is all about matching the right diameter to the job for accuracy and consistency. My biggest takeaway is that even a small difference in size can affect fit, threading, and overall results. When I double-check the measurement before drilling, I save time and avoid mistakes.

Author Profile

Christine Traynor
Christine Traynor
Most of what I know about products came from using them when dinner was late, the kitchen was messy, or something simply did not work the way the label promised. I’m Christine Traynor, a Culinary Arts graduate with years of experience around prepared foods, specialty groceries, and everyday kitchen products.

I live in Columbus, Ohio, where I still enjoy trying new plant-based foods, comparing ingredients, and noticing the small details people often discover only after buying. Eat Vegan Vybez grew from that habit. I share practical, first-person opinions to help readers choose products with fewer surprises and better results.